Added to_dict to serializable models

* Submission and TestRequest now have to_dict methods for serialization.
Fixed logical typos in FlockManager

* Modified SheepInfo namedtuple to have correct definition
* Modified manage_sheep to use correct type for Flock identity
* Modified check_environments to use correct arguments
Shepherd distributes requests to sheep for #149

* Modified match_found to send a proper serializable request message
Merge remote-tracking branch 'upstream/v0.2dev' into v0.2dev