Changes for rc1.
Merge pull request #343 from bjlittle/release_1p2_rc1

Changes for rc1.
Revert Iris version from 1.2.0-rc1 back to 1.2.0-dev.
Merge pull request #347 from bjlittle/release_1p2_rc1_dev_version

Revert Iris version from 1.2.0-rc1 back to 1.2.0-dev.
Default tests to the 'agg' matplotlib backend.
Update module docstring
Merge pull request #354 from rhattersley/headless-tests

Default tests to the 'agg' matplotlib backend.
Prevented the ability to add AuxCoord instances to the dim_coords.
Merge pull request #358 from pelson/type_of_dim_coord2

Prevented the ability to add AuxCoord instances to the dim_coords.
travis: cartopy 0.6
version 1.2.0
Merge pull request #379 from bblay/v1.2.0-release

V1.2.0 release
version 1.2.1-dev
Merge pull request #380 from bblay/v1.2.1-dev

version 1.2.1-dev
Merge remote branch 'upstream/v1.2.x' into HEAD

Conflicts:
	.travis.yml
	docs/iris/src/whatsnew/1.2.rst
	lib/iris/__init__.py
	lib/iris/cube.py
	setup.py