Adding repos in Jarvis.

[hariharan-devarajan]

We need to have a repository namespace resolution:
Essentially:

• create folder structure of var/jarvis/repos where all prebuilt repositories would be present.
• By default, we should have a builtin repository folder in Jarvis.
• The list of all repositories add in jarvis will be stored in etc/jarvis/repos.yaml similar to link
• Adding a new repo will update the file at etc/jarvis/repos.yaml
• We need a Repository entity which will load and serve a repository
• We need a RepositoryManager which will maintain a list of all current repositories and instantiate the Repository entity.
• We need a schema finder module that will locate a given schema from all existing repositories.

Each repository:

• should have repo.yaml (fixed name) : similar to link
• and a schemas folder that will contain all the deployment schemas as we have now.