Modified comp_map.draw_limb to find first map with rsun attr.

Also forcibly set zorder in map.draw_limb() to make it on top of comp map
Added default index code to draw_grid.

Same as last, also added zorder=100 to map.draw_grid()
Changed C extention print to ImportWarning
More changes to index
Added exceptions to composite map draw_grid + limb
Changed Crotate fail behaviour: issue #390
Changed warning to not raise error.
Chenged ImportWarning to Warning as import Warning is ignored by default.
Added a notes section to map.rotate() docstring.
Modified troubleshooting section in docs
Tidying up docs
Remove debugging if True:
built--> compiled
Merge branch 'staging' into cube_ani

Conflicts:
	sunpy/map/compositemap.py