Add status bar offset on iOS 7

As the status bar is part of the interface from iOS 7 on, we need to add the offset in certain cases, so that the message does has some more padding.
Merge pull request #62 from toco/master

dismiss endless messages when the view controller is dismissed
Merge pull request #61 from dennisreimann/master

Add status bar offset on iOS 7
Added automatic use of rootViewController when no VC was set

Fixed example project layout on 3,5"
Add an iOS 7 style check when setting the vertical offset for notification inside UINavigtationControllers.
Merge pull request #64 from mikeplaced/master

Add an iOS 7 style check when setting the vertical offset for notification inside UINavigtationControllers.
[Bugfix] in iOS 7 the notifications slipped under the UINavigationBar. I fixed this issue here.
Merge pull request #66 from mRs-/bugfix-notifications

[Bugfix] in iOS 7 the notifications slipped under the UINavigationBar. I...
Remove any background image set through the appearance proxy.
Added new iOS 7 screenshots
Merge branch 'master' of github.com:toursprung/TSMessages
Merge branch 'master' of github.com:toursprung/TSMessages
Fix compile error using iOS SDKs before iOS 7
Adding HexColors as a submodule
Updating README with HexColors information (if using submodules)
Merge pull request #71 from runmad/master

Fix #63: Adding HexColors as submodule
Merge pull request #69 from wangyandong-ningxia/master

Fix compile error using iOS SDKs before iOS 7
Example Project updated
Merge pull request #73 from mRs-/HexColors2.2.1

Example Project updated
Remove the message view underflow if the navigation bar is not opaque.