Version bump. [ci skip]
Fix for issue #68: pass string for type.
Merge pull request #69 from mcmtroffaes/feature/fix-fake-type-for-pybtex-0.18

Fix for issue #68: pass string for type.
Prepare release.
Merge pull request #70 from mcmtroffaes/release/0.3.1

Release 0.3.1.