enable ios 8 compatibility by being able to trust status bar dimensions

In iOS 8 status bar height and width are actually correct no matter the orientation now. Same for all UIWindows as well.

Fixes #28
Add ios 7 compatibility to fix for ios 8 status bar widths
Merge pull request #29 from DocuSignDev/feature/ios8-status-bar-size

Fix iOS 8 status bar width