Remove warning from ctypes

RuntimeWarning: C function without declared arguments called
Better docs for rotate().  Fix #57
Moved file reading code from Image.__init__() into Image.read() method
Added changes to allow empty Image constructor
Added Image.clear()
Added tests for Image.clear() and Image.read()
Updated description in Image.read() and Image.clear()
Fixed exception checks in Image.read()
Added Image.resolution getter/setter
Merge pull request #58 from pflorczyk/read

Added Image.read() and Image.clear()
Coding style #58
Changelog for #58
Moved blank image generation from Image.__init__() to new method Image.blank()
Merge pull request #60 from pflorczyk/master

Added Image.blank()
Changelog for #60
Install guide for FreeBSD
Raise ImportError if the library cannot be found
Release 0.2.2
Merge branch '0.2-maintenance'
Fine error message for lack of ImageMagick