Polishing UI: minor improvements (mainly for mobile UI)

[hisinbox]

Describe the bug
list of minor UI bugs mainly related to mobile view

1. • Markets: add back "Vol." to the second row of the first column
2. • Markets: Remove volume currency indicator "$" from the second row of first column
     2.1 - [] Markets: add search icon/feature to mobile markets
3. • Order history: scroll gets stuck on mobile view
4. • Mobile popups: closing cross is too small, enlarge (see cross on Account burger active screen)
5. • New order heading: heading style (height and font) should be the same in the heading of tab screens (eg markets)
6. • New order embedded widgets: click on open widget should close it
7. • New order embedded widgets: let's make style of widgets headings same as screen headings (bold etc)
8. • New order embedded widgets: the last widget (history) is too low, partially faded and hard to click
9. • New order embedded widgets: click on the heading should open screen with heading CHOOSE MARKET in the center and back arrow on the left (instead of now opening simply markets tab)
10. • My orders: if active or history is empty - the signs No Active Orders or No Orders In History should be centred vertically on the screen (currently to close to tabs)
11. • My orders: pairs' name second row should start with slash "/" like on markets
12. • Global change: all lists (list of order on My Order, list of assets Assets on Account) should be separated with horizontal lines like on Markets
13. • Account: second column (Balance or Prices) is to close to the first column - let's shift it to the center between two columns
14. • Account: When Hide Small Assets is activated show grey link under the list of assets "Show Balances Above $5", click to show (and when there are no large assets show same link in the center of empty screen)
15. • Account: When there are no large and no small assets in the account (new account) show grey link "Buy Assets" click sends to markets tab
16. • Account: lets make the Deposit / Withdraw / Transfer wider - so that space between buttons is small. see mockup [https://app.zeplin.io/project/5ba4e8c9a61c41288762b16b/screen/5bd9f3a8845b5a2662019e28]
17. • Market: make more space for Start tab - same width as for USD/BTC markets - ie more space from the left and right of Start tab; realign the whole markets selection tab to the right of the screen (to make i easier to click with right finger)
18. • Markets: when Star tab is selected and the are no favorite assets, show link "Add BTC/USD to favorites", click will open new order for BTC/USD and auto-click star button in the heading"
19. • Withdraw / transfer / deposit: clean field button (cross) doesn't work
20. • Withdraw / transfer / deposit: let's use same font / style for all the screens headings, same for tabs and inside screens (maybe create a component)
21. • Markets: scroll is not smooth and when the list is ends scroll should behave differently (like native scroll - responsive)
22. • My Orders: Let's enlarge the plus (create order) button - make it same style as on the account burger menu)
23. • My Orders: Let's increase the space above columns' headings (make it same as above column headings on the Account)
24. • Account: do not freeze scrolling of BALANCE and hide / show buttons, freeze just scroll of buttons
25. • Markets: Let's increase the space above columns' headings (make it same as above column headings on the Account)
26. • Markets: Show BTC equivalent in the second row of second column when USD tab is activated (currently show same - duplicates - figure in USD)
27. • Unlock screen: need to unify unlock screen across the app (see issue about PIN/Password)
28. • Unlock screen: toaster notification on backup unlock screen is not working properly on mobile

Smartphone (please complete the following information):

• Device: iPhone7+
• OS: iOS8.1
• Browser Safari

[hisinbox]

@noeminik please check - maybe makes sense to create separate issues on some of the points - either way can use also as a checklist