Camera permission behaviour

[ippschi]

Addresses #488

• Important: Old behaviour does not change. If library is used as before, behaviour does not change
• Showing the dialog if permission is missing is optional now but true as default (as before)
• Message can be set optionally, either programmatically or via IntentIntegrator
• New Activity result is set if permission is not granted
• Programmers can react on the onActivityResult Intent and modify if a dialog should be shown by the library directly or not
• Removes SDK 23 version checks since library uses API 24

[rkistner]

Thanks for the PR. The library currently still supports "downgrading" to SDK 14, so we'll still need those API checks.

I'll review the rest in detail a little later.

[ippschi]

I reverted the removal of the API checks to allow downgrading to SDK 14.

[rkistner]

@anipp100 Thanks for the work. I haven't forgotten about this - will try to get to it soon.

[rkistner]

Thanks, released in 4.1.0.