Fix for system colors on OSX

Untested since I can't run bundle exec rake spec platform=osx properly in RM 2.37 on Yosemite. Errors out with:

2014-10-30 12:24:27.960 SugarCube[15846:2228237] Failed to connect (colorGridView) outlet from (NSApplication) to (NSColorPickerGridView): missing setter or instance variable
2014-10-30 12:24:27.960 SugarCube[15846:2228237] Failed to connect (view) outlet from (NSApplication) to (NSColorPickerGridView): missing setter or instance variable
2014-10-30 12:24:28.346 SugarCube[15846:2228237] *nil description*
Remove unnecessary selector check.
Merge pull request #173 from MohawkApps/nscolorspace

Fix for system colors on OSX
presentationStyle / transitionStyle

Add presentationStyle and transitionStyle to present_modal
Merge pull request #174 from bmichotte/modal-presentation-styles

presentationStyle / transitionStyle
fixes system colors and adds :presentation and :transition options to 'present_modal'
added SpriteKit docs, more methods, and specs!
adds specs for NSAttributedString additions, and adds 'subscript' and 'superscript' methods
demoing superscript
notes RE: Repl package
not necessary (added by 'sugarcube-corelocation' package)
finished writing specs for NSAttributedString - on ios AND osx
rm debug output
bump for NSAttributeString fixes
Adds method on NSString to generate an NSAttributedString from html.
Merge branch 'master' into nsattributedstring_from_html

* master:
  bump for NSAttributeString fixes
  rm debug output
  finished writing specs for NSAttributedString - on ios AND osx
  not necessary (added by 'sugarcube-corelocation' package)
  notes RE: Repl package
  demoing superscript
  adds specs for NSAttributedString additions, and adds 'subscript' and 'superscript' methods
  added SpriteKit docs, more methods, and specs!
  fixes system colors and adds :presentation and :transition options to 'present_modal'
  presentationStyle / transitionStyle
  Remove unnecessary selector check.
  Fix for system colors on OSX

Conflicts:
	lib/cocoa/sugarcube-attributedstring/nsattributedstring.rb
Update readme.
Merge pull request #175 from MohawkApps/nsattributedstring_from_html

Adds method on NSString to generate an NSAttributedString from html.
2.12.0 - adds @markrickert's HTML support to NSAttributedString, and a little more README
quote matching in README