Refactored implementation of local deletions.

Handling of pending deletions (for replication) is done by a store adapter.
Replication implementation has been straightened and augmented with comments.
Reworking publish settings dialog. Pt. 1.
Merge branch 'master' of github.com:substance/composer
Implemented create version workflow.
Make unpublish work.
Cleanup.
Store creator as along with document metadata.
Introduced some smaller hacks to make the annotation toggles work seamlessly.
Implemented collaborators.
Use linked external source files.
Updated .gitignore.
Add a script that simplifies build configuration.

Externals are now shared between all substance related modules (composer, hub, store).
Remove obsolete copies of external source files.
Bundle linked source files.
Updated install script.
Updated install script.
Updated install script.
Updated .gitignore.
Ignore linked tests folder.
Grauslich.