Fix tether and dropdown-direction compatibility with bootstrap

[howardjing]

I ran into some issues with using the following properties:

• tether
• dropdown-direction

when using react-selectize within an application with bootstrap3 css included.

The issue seems to be a clash between bootstrap and react-selectize over the .dropdown-menu class name. I renamed dropdown-menu to rs-dropdown-menu as a sanity check, and it fixed the issues I was having.

I don't think this current PR is a great solution as it would break any existing customized css people have made for the dropdown menu, but this was the quickest fix for my purposes.

@furqanZafar I'd appreciate your input as to what you think is the best way to solve this.

See #137 for more details.

[coveralls]

Coverage decreased (-4.6%) to 86.012% when pulling ffe679b on howardjing:dropdown-css into 9e936fa on furqanZafar:master.

[htsui]

I've put this PR up on npm under 'react-selectize-bs'

[Gribbs]

react-selectize-bs fixed the issue for me! Thanks

[hwaterke]

react-selectize-bs doesn't solve the problem and is already several versions behind.
I think this needs to be merged. It is anyway not a good idea to use very generic css classnames in such a component.

[mnieber]

I see the changes were approved, great :-). @bruno-sartori @howardjing is this a matter now of rebasing the branch?

[howardjing]

Ah, thanks for the heads up. I'll update the PR later today.

[howardjing]

#187 has the rebased code