UMS: updateUser now checks if email parameters are valid

fixes #406
Fixed miscs problems
  ** The default value of user privilige in EMF objects is not longer 0. Indeed, that was a cause of troubles to know if user set privilege when running vishnu_update_user
  ** A control is now introduced concerning the status a account when updating the user account. Previously, it was possible to delete a user like this : vishnu_update_user <user> -s 2.
     And with other status than 0, 1 or 2, it was subject to segfault.
  ** Removed the including of namespace std in the header of ums_api.cpp
FMS: add a global transfer timeout parameter

Since scp and rsync have unlimited timeout,
we allow users to define a global timeout parameter (default: 0/unlimited)
fixes #396
FMS: set default global transfer timeout parameter value
FMS: add documentation for VISHNU_TRANFER_TIMEOUT option
UMS: register VISHNU_TRANSFER_TIMEOUT option and value check