This makes the local storage provider "answer" the relation when a mountpoint
is requested. Without this, the local provider will never ping back the main charm
and so most likely the main charm will hang forever.
Added os.makedirs() call on the mountpoint to make sure it exists.
Merging lp:~tribaal/charms/precise/storage/make-local-provider-answer

The local storage provider now answers the main charm immediately (since no IO
is actually necessary).  [r=davidpbritton,stub,lazypower] [s=tribaal]
[f=lp:1357684]