Fix 'ghc-show-info' when cursor is on space

'ghc-show-info' asks for user to enter expression if 'ghc-thing-at-point'
returns nil. Because 'ghc-display-information' failed such case.
Merge pull request #91 from syohex/fix-show-info

Fix 'ghc-show-info' when cursor is on space
ver bumps up.
adding .travis.yml.
adding tests.
more proper name.
test for Flag.
test for Browse.
hlint hack.
test for Lint.
test for Cabal and CabalApi.