implemented Shares resource and the add_share method
check if an user can write in a (shared) directory
share as specifications: resource name in url, shares only in top level directory
shares' delete user and resource
share in push and rm path
modify management in share
test: creation of some clients to test the share
added test for create share + bugfix on a reference in server
added test can write, to check
test share: remove_beneficiary. Some pertinent fixes in server
tasks and examples
test share: changes in a shared resource
added can write control in delete and post (file upload)
added can_write test
merge of share test
fixed useless test line+
fixed merge errors
fixed some merge errors
fixed can_write test about delete
PEP8 added style