Add update-bower.sh and update bower.json of all exercises

[icyrockcom]

Continuation of #71.

Fixes this:

• Fix each of the exercises (it should be only copying the bower.json, but need to confirm)
• Add a script to copy the common bower.json to all exercises to help with the development

Remaining:

• Add dependency checker to the build which would confirm that all exercises are using the same versions as the common bower.json
• Update documentation for contributing to mention the additional restrictions

@lpil please check it out if you have a moment.

[lpil]

Dig it

[lpil]

Thanks!

[icyrockcom]

Thanks @lpil!