chore(scripts): inform when no tag available

The test is based in the $TRAVIS_TAG env var, made available
by Travis only when running in a tagged commit.
feat(navbar): create the static navbar style

Closes #58
Merge branch 'static-navbar'
feat(tooltip): create tooltip directive
style(tooltip): add a few comments
test(tooltip): create complete test suite
docs(tooltip): write about what is it
feat(tooltip): parse interpolation

 Use Angular interpolation feature to parse the element's title
attribute.