Add Bower as a devDependency to package.json

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Peg readable-stream to 1.1.11 in package.json

(a bower > decompress-zip dependency)

1.1.12 is failing on CI.
See:https://github.com/isaacs/readable-stream/issues/89

Signed-off-by: Alex Coles <alex@alexbcoles.com>