Eliminate angular-bootstrap dependency

[grtjn]

See https://github.com/patrickmcelwee/ml-visjs-graph-ng/blob/master/bower.json#L15

From what I can see, angular-bootstrap is not being used, only plain bootstrap css.

[grtjn]

ml-visjs-graph-ng uses bootstrap grid layout (col-md-12 etc). That should be eliminated, or we should add bootstrap css to bower.json (instead of angular-bootstrap).

By the way, looks like dev on angular-(ui-)bootstrap has been ended, in favor of angular 2 ng-bootstrap. Another reason to not want to include it..