Validate Election Manifest and Descriptions #127

Feature Request

Is your feature request related to a problem? Please describe.
Election Manifests are essential to the election process but are easily to input incorrectly.
This would allow some type of verification to ensure that a user can check the manifest.

Describe the solution you'd like
Implement the validation present in the lower level electionguard-python

• use Serializable parse method
• use ElectionDescription is_valid
• use validate_json_schema