Use browser-modules as submodule

This means we don't have to maintain two copies of
the same library.
Add a couple of tests around relative requires for blades
Move "bootstrap" to public static String
add travis file
fixing issue where bootstrap couldnt depend on another library
making browser-modules a seperate library and changing br-bootstrap so it depends on browser-modules
Merge pull request #318 from BladeRunnerJS/browser-modules

Adding Browser modules as a submodule and changing br-boostrap to depend on that library
Merge branch 'bundler-exploration' into testPackImplementation

Conflicts:
	brjs-core/src/main/java/org/bladerunnerjs/utility/BundleSetBuilder.java
removing some util methods we dont need anymore