v2.0.0rc1

This is the first release candidate for mpl v2.0

This release includes:

• A re-implementation of the way margins are handled during auto
  scaling to allow artists to 'stick' to an edge of the Axes
• Improvements to the ticking with log and symlog scales
• Deprecation of the finance module. This will be spun off into a stand-alone package
• Deprecation of the 'hold' machinery
• Bumped the minimum numpy version to 1.7
• Standardization of hatch width and appearance across backends
• Made threshold for triggering 'offset' in ScalarFormatter configurable
  and default to 4 (plotting against years should just work now)
• Default encoding for mp4 is now h264
• fill_between and fill_betweenx now use the color cycle
• Default alignment of bars changed from 'edge' to 'center'
• Bug and documentation fixes