fixes #157: attribution improvements & fixes from @ryanmaxwell
Fixes RMShape bezier drawing for below iOS 6.

I just changed use of NAN to INFINITY, which is available in
earlier versions of iOS.
fixes #155: don't crash on nil static map handler
Merge pull request #162 from tmalloy/rmshape-bezier-nanfix

Fixes RMShape bezier drawing for below iOS 6.
fixes #153: added podspec for direct CocoaPods use
Merge branch 'develop' of github.com:mapbox/mapbox-ios-sdk into develop
fixes #158: add support for callout subtitle via annotation subtitle
defer to delegate for simplestyle annotation layers if available
fixes #159: programmatic callout display/dismiss & callout API improvements
refs #166: passthrough calloutOffset
fixes #166: callout fixes for shapes & circles
refs #166: do shape hit detection based on painted areas
update downloads link
refs alpstein/route-me#120: use proper map bounds for shape clipping
link to guide for install options
include more info about sub-libraries used
resolve some very subtle memory problems under non-ARC
fixes #169: allow re-add of annotations
Merge branch 'develop' into release