Use new typesafe enum macro. Run analyzer.

This helps guarantee that all switch cases are properly handled.

Assumed that SVPullToRefreshStateAll should be treated the same as SVPullToRefreshStateStopped in existing switch statements, since SVPullToRefreshStateAll is an invalid state for those. assert(NO) would also be appropriate.

Turned on static analyzer since defining the SVPullToRefreshStateAll cases in existing switch statements fixed all analyzer warnings.
Fixed issue where pull to refresh view would not hide cleanly
Fixed a potential KVO crash.

The contentSize keypath should also be removed when showsPullToRefresh is set to NO.
Added support for setting the color of the UIActivityIndicatorView.
Added availability constraint to UIActivityIndicatorView color property.
Animate activityIndicatorView as soon as the view appears
Fixed an animation problem on iOS 7

Immediately layout subviews when changing state, otherwise changes in layoutSubviews will be animated on iOS 7.
Avoiding to add a margin to the arrow when the title text is empty. This will make the arrow centralized in the screen when there is no text.
Merge pull request #143 from bdbergeron/master

Add support for setting UIActivityIndicatorView color (iOS 5+)
Merge pull request #152 from michelzanini/master

Centralise arrow when the text is empty
Merge pull request #133 from nonamelive/master

Fixed a potential KVO crash.
Merge pull request #144 from alanzeino/master

Animate activityIndicatorView as soon as the view appears
Merge pull request #132 from otherinbox/master

Fixing issue #131
Merge pull request #127 from hborders/typesafe_enum_and_analyzer

Use new typesafe enum macro. Run analyzer.
Merge pull request #125 from jweyrich/master

Fix unitialized variables. Remove unnecessary type-cast.
Update project settings.