(Fix) Empty pending tx screen after logout/login

[vbaranov]

Relates to #68

The root cause of the issue is that context prop contains not the index of pending tx, but the context from the previous screen (current unlocked address), when we attempt to login after logout.

Solution:

• context prop is replaced with pendingTxIndex prop.
• if pendingTxIndex is undefined, as in the case from logout/login, it is set to 0. So, the first pending tx will be displayed in the list, if pending txs exist.

Also, view of pending contract creation screen is configured to match the style of pending screen:
Before:

After: