Expanding tag name to avoid HTML parsing issues, switching to bower.json, updating Angular dependency

The `grunt-contrib-htmlmin` task throws a parse error when run on an HTML file that includes the `<g+signin>` tag. This pull request avoids this and other syntax-related issues that come from using a `+` in the tag name, by expanding the name to `google-plus-signin`.

I also renamed `component.json` to `bower.json` to silence the deprecation complaint from bower, and updated the dependency version on Angular. If these changes are not desired, I can branch on an earlier commit and update the PR.