readium-shared-js integration
Display current page number
display/update viewer settings such as column gap, font size and synthetic spread
Merge branch 'develop' of github.com:readium/Launcher-Android into develop

Conflicts:
	readium-shared-js
Fixed some issue with needing v4 lib exported in the project and added a closeBook() when exiting BookDataActivity to test release of native memory.
Updated submodule readium-sdk to point to current develop commit
Merge branch 'feature/txtr-s1-sharedptrs' into develop
Merge branch 'develop'