release 1.2.0

release 1.1.0

Add python_requires header

Update CHANGELOG for 0.15.1

Update CHANGELOG for 0.15.0

Prepare CHANGELOG for 1.14.0

Fix 'docs' tox environment and change warnings into errors

Also runs the 'docs' job on Travis to ensure documentation is building
correctly.

Prepare CHANGELOG for 0.12.0

Add syntax highlight to example in README