Fixes warning when compiling for iOS 7. Replaces deprecated NSString class method sizeWithFont: with sizeWithAttributes:.
Added setPlaceholder method to call setNeedsDisplay
Fixed placeholder not updating after being set.

Fixes issue #68
Merge branch 'master' of https://github.com/HansPinckaers/GrowingTextView

# By Alexey Sariy
# Via Alexey Sariy (1) and Hans Pinckaers (1)
* 'master' of https://github.com/HansPinckaers/GrowingTextView:
  Use __IPHONE_OS_VERSION_MIN_REQUIRED macro to make it actually work on iOS < 7.0
  Should build with <7.0 SDK
  Add ability to create internal text view with custom text container
Added ability to center placeholder based on NSTextAlignment of the InternalTextView.  This is a partial implementation for iOS 7 only.
Merge pull request #69 from danpe/master

Fixed placeholder not updating after being set. #68
Merge pull request #62 from InboxAppCo/master

Fixes iOS 7 warnings & adds ability to update Placeholder
fix distorted placeholder by setting contentMode to 'redraw'
Merge pull request #74 from hoccer/fix_distorted_placeholder

fix distorted placeholder by setting contentMode to 'redraw'
更新作者代码