Revert API change for 2.9

This changes the ProjectInfo class back to its old location, which
allows the plugin to build with stable-2.9.  This does require the
v3.4.0 version of JGit to ensure it can register ArchiveFormat
(https://git.eclipse.org/r/24887).

Change-Id: I944998515e47bb18a08a46e32e738668111e5edf
Depends-On: I57e95d09e87a0eca53735638da2a0ebbf30d9349
Depends-On: Icb80a446e583961a7278b707d572d6fe456c372c