Correct .gitignore syntax and remove compiled bootstrap.json file at root.

Prior to this commit, the git repo was omitting files from the
generated directories (build/, phonegap/, node_modules/) but not their
respective subdirectories. This commit corrects .gitignore syntax to
ensure these subdirectories do not get re-introduced to the project.

This commit also removes the bootstrap.json file at the root of the
project as it is also generated on 'sencha web start' and 'sencha app
build'.
Add native/ directory to .gitignore

New Sencha Cmd versions will output local cordova/phonegap build
results to a directory called "native" at the project root. This
commit adds a clause to the .gitignore to ensure that this new build
directory does not pollute the repo.
Remove bootstrap.js and resources/css/app.css from project

The bootstrap.js and resources/css/app.css files were included in the
.gitignore file as they are compiled resources, but they were not
actually removed from the project repository. This commit removes
these files from the repository.
Merge pull request #12 from osu-cass/maint-gitignore-buildfile-subdirectories

Maint gitignore buildfile subdirectories