Revise and add to docs everywhere except mediation.

I had to import `android.view.ViewGroup' into the interstitial ad view
file to get the Javadocs to build.
Cleanup xml description

Documentation change
Revised & updated docs in mediation-related files.
MS-124 remove retrying requests from SDK
MS-124 unit tests updates, move package
MS-397 updating debug auction in app to show device info.
Merge remote-tracking branch 'origin/master'
MS-124 return null for no network or context case.
Merge branch 'ms124'
MS-385 make display protected in InterstitialAdView to hide from javadoc
MS-386 refactored mediation to create private displayable object, hide inner classes from javadoc
MS-386 update interstitials for new MediatedDisplayable
MS-386 CR-159 use private variables
MS-398 use last request as base url for debug auction
Update gitignore
MS-390 Application crash on invalid API

setScaleX requires API 11
setLayoutDirection requires API 17

Changed play button rendering to use Matrix rotation
Tweaks for crash fix from Ron
MS-124 remove retrying requests from SDK
MS-124 unit tests updates, move package
MS-397 updating debug auction in app to show device info.