feature: when using LdapUserService one can configure Gitblit to fetch all users from ldap that can possibly login. This allows to see newly generated LDAP users instantly in Gitblit. By now an LDAP user had to log in once to appear in GitBlit.

feature: when LDAP user synchronization is enabled, one can configure GitBlit to delete all LDAP users from the backing user service that are no longer existent in LDAP. By now LDAP users that were deleted still appeared in the GitBlit user list.
significantly reduce write operations to backing user system.
Merge branch 'master' of https://github.com/gitblit/gitblit into enhancedLdap

Conflicts:
	distrib/gitblit.properties
cache results of LDAP user synchronization for a configurable amount of time (realm.ldap.ldapCachePeriod = 2 MINUTES)
FIX: setting line separator back to Windows style
Merged LDAP user/team pre-fetching and synchronization enhancement from mschaefers