zendesk: prettify the details field

Skip blank attributes.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
config: document and fix database configuration

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
user_updater: add some comments

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
endpoints: add convenient endpoints to update accounts and retrieve mappings

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
Rakefile: fix default task

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
test: fix remote test issue with Singleton pattern

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
Merge branch 'master' of github.com:killbill/killbill-zendesk-plugin