Update README.md

Fixed Bootstrap variables link to http://getbootstrap.com/customize/#less-variables
Updates Bootstrap link

URL to http://getbootstrap.com/
update Flatly for 3.0.0

Fixing the following styles in Flatly.

* **Removing the blue `box-shadow` & add border to form elements and
making them like original Flatly**
* Fixing the background color of:
  * Well
  * Navbar Input and Toggle
  * Nav Tabs
  * List group
  * Panels
  * Breadcumbs
  * Pre
* Remove the `box-shadow` of the `:active` button state.
* Pagination & Pager hover link was fixed.
* `box-shadow` from well was removed.
Merge pull request #138 from jenil27/gh-pages

Update Flatly & Readme links