Fix crash related to non existent primary key
Fix boolean tests
Looks better now
Useless import and bad dictionary creation

That dictionary is faster (slightly) now and I find it more readable.
Typos, shadowing of str (built-in), useless imports
Merge pull request #77 from mafagafo/master

Minor improvements
Fix primary keys tests
Merge pull request #76 from noplay/fix_unit_tests

Fix unit tests
Travis CI
Complete documentation
Fix tests
Merge pull request #73 from noplay/travis

Travis CI
Complete documentation
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