Added Modal Service and refactored previous usages

Summary: Bootstrap modal extension as a service.

Test Plan: should dismiss all modals on route change

Reviewers: kabaros, albertkang75

Reviewed By: albertkang75

Differential Revision: http://178.62.60.45/D36
Removed unsed file
Fixed test
Merge commit '7feb3ccb0e1e6c803152c625e7e930b874ce3f5c' into HEAD