make tag-release script change dist folder also

This pull request is to make `tag-release` script change/tag also the dist folder files and bower.json before the next tag is applied. And when the tag is commited, dist folder will be removed.

Added:
 - check for existence of dist folder
 - dist files and bower.json will also be tagged
 - dist folder is removed after 1.5.x tag and before “1.5.x-dev” tag