Merge pull request #306 from reneme/replace_lockguard

Replace LockGuard and LockGuardAdapter by a More General RAII Template

It turns out, that my LockGuardAdapter template was broken and relying on undefined behaviour. This totally gets rid of it and replaces the former LockGuard by a more general RAII wrapper class.
start development of cvmfs python library
add .cvmfspublished into _common
abstract Repository for addition of 'RemoteRepository'
add a manifest (.cvmfspublished) abstraction class
add remote repository support
adapt global collection functions
FIX: non-available RemoteRepository throws HTTPError
set manifest field 'L' as micro catalog
add REST specific information to _common
replace urllib by requests
add REST specific query methods
read last snapshot timestamp if appropirate
figure out cvmfs binary versions in python
store server version in Repository object
figure out if stratum 1 is currently snapshotting
refactor get rest requests
add a 'start_replication' method in RemoteRepository
minor refactoring in RemoteRepository