Improve cache logic (for ~/.m2 use)

Remote downloads now cache their jars to the users
~/.m2/repository for use in subsequent runs. With
this in place, offline builds will succeed as long
as one build has taken place before going offline.
Only load own tags if in read only group
Don't load owner information for empty tag list
Fix licenses/README whitespace
Fix whitespace in lifecycle.xml
Set type='jar' for ivy:retrieve

Without an explicit type reference on the general
call to retrieve, poms are also copied to targets/libs
which are cause zip exceptions when added to the classpath.
merge develop -D org: PR 2127 (Working view to email announcements to selected users, groups, email addresses and/or all users)
merge develop -D org: PR 2256 (Tablet drag handling)
merge develop -D org: PR 2258 (Truncate js tree dynamically 12161)
merge develop -D org: PR 2269 (ROI improvements)
merge develop -D org: PR 2336 (New tagging dialog)
merge develop -D org: PR 2357 (Generate Python API reference with Sphinx)
merge develop -D org: PR 2362 (Remove .jy from script names)
merge develop -D org: PR 2391 (Imagej omero (rebased onto develop))
merge develop -D org: PR 2403 (Send email)
merge develop -D org: PR 2428 (Move kill session to global teardown)
merge develop -D org: PR 2435 (cpp: RTypesI: use static locals in place of duplicated globals)
merge develop -D org: PR 2446 (Enable multi-select in Tags tree)
merge develop -D org: PR 2450 (Run session creation in system context)
merge develop -D org: PR 2455 (Remove support for Ice 3.3)