release sunpy v0.6.1

Release SunPy 0.6

bump to version 0.6 beta 1

updated changelog

Release 0.5.4

Release 0.5.3

Mock out glymur for doc build.

Mock glymur if glymur or a backend is not installed.

Change version number to 0.5.1.

Release 0.5.1

remove redundant exception docs from database.rst

This works-around a werid doc bug. see astropy/astropy-helpers#37

Fix docstring in map.rotate()