chore(travis): fetch git tags before deploy

 As a workaround to try to avoid Travis 'tag_name not well formed'
 problem when deploying, we'll fetch git tags before doing so.
 For reference, see travis-ci/travis-ci#2510.
docs(contributing): create a contribution guide

Close #60
feat(overlay): add new mixin .make-overlay()

As the current offcanvas overlay is likely to be used in other places
as well, we're moving it to a separate mixin, with an optional position
argument.
refactor(overlay): ensure it uses display: block
feat(overlay): create the overlay component
fix(docs): don't overflow content in examples
chore(package.json): update dependencies to latest versions
chore(bower.json): set homepage

Bower warns that we don't have a homepage set in our manifest.
So, let's do this to make it happy :)
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.
Merge branch 'tooltip'
docs(tooltip): fix example code to match what is shown

We we're showing a <a> tag, while in the example code we have
a <abbr> tag.
chore(bower): remove normalize.css from deps

To have the most flexible environment possible, we are now
including normalize.css in the repo and removing it from the
bower.json manifest. normalize was only needed when using
 the source .less files, what probably won't be the case of most
 developers.

 Fixes #61
chore(bower): use different bower manifest for releases

Up until now we were using the bower.json available in the
repository root, which was bloated with development and docs
dependencies, not needed by anyone using the Frontkit's bower
release.