LVMShareDriver: pluggable load of helpers

Change-Id: If35e21adc23206bc3fda8cb06944b2d0cf2b470f
ShareManager: add service_name as init argument.

Change-Id: Ie272a28d0186623472a11ea5959296bc5bba4f10
LVMShareDriver: try to mount in ensure_share.

Change-Id: Ib0e6b1c3fffdfdad11f222511d14af7fc85213f0
Add CIFSNetConfHelper to control smb by net conf.

Change-Id: I220056ec124e0962be63e293e19eb1f9b1bf1d7f