[tests] Adds Jasmine submodule, rake tasks

Adds `rake deploy:offline` task, which deploys Jasmine to client/lib/,
     where it should exist to run the spec examples.

Adds client/SpecRunner.html, which is what you should open to exercise
the Jasmine specs.

Adds tasks/rake_helper.rb, moves some commonly used functions into the
RakeHelper module, adds the GitHelper class, an API that wraps up the
git boilerplate to safely do common git operations in rake tasks.

Modifies .gitignore to ignore vim swap files and anything placed in the
client/lib/ directory, since that can be reproduced by the
`deploy:offline` rake task.

Modifies every rake file to fix broken references to old rake helper
functions.