Add RPC calls to WConfd to lock/unlock ConfigLock
Add RPC calls to WConfd to lock/unlock ConfigLock

This allows the clients to protect configuration operations, as required
by the current implementation of Python 'ConfigWriter'.

Signed-off-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

bitemyapp/ganeti,leshchevds/ganeti,andir/ganeti,yiannist/ganeti,andir/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,yiannist/ganeti,dimara/ganeti,onponomarev/ganeti,mbakke/ganeti,mbakke/ganeti,ganeti/ganeti,dimara/ganeti,bitemyapp/ganeti,leshchevds/ganeti,andir/ganeti,grnet/snf-ganeti,onponomarev/ganeti,yiannist/ganeti,mbakke/ganeti,apyrgio/ganeti,ganeti/ganeti,ganeti/ganeti