Beta make file should be tied to specific module versions

Currently the openatrium make file is bringing in the latest -dev versions of various submodules (oa_core, oa_events, etc). Instead, this Beta make file should be tied to specific Beta versions of submodules. A separate -dev.make file should be created for use in -dev versions of the profile. This will allow people to install the Beta version in the future without getting newer, possibly incompatible versions of submodules.