fix metadata retrieval containing empty values

Sometimes metadata can be set, but its value can be empty (for example
when a property is removed).
Merge pull request #16 from alvarolopez/master

fix metadata retrieval containing empty values
Removed python-novaclient dependency.
Release 0.5
Add an option to generate site-BDII provider LDIF.

This new option should be used only in the case
that the cloud-info-provider is executed as
one of the providers of a site-BDII (not recommended
in production)
Moved to a function the logic for getting the suffix.
Added test for the new _get_suffix function.
Allow to specify the templates schema.
Merge branch 'master' of github.com:enolfc/cloud-bdii-provider