Repurpose mepo init

[pchakraborty]

The init command is somewhat odd. In the current implementation, all it does is read components.yaml and create the state (.mepo/state.pkl). In the original design, it was meant to be followed by mepo clone. Since clone now has init folded in (i.e. has the ability to initialize the state), the standard way of using mepo is to start with the clone command

mepo clone -b <version> <url> <directory>

So it is possible to use init for some other purpose. For example, it can traverse a directory tree that has been manually prepared, find .git directories and create the registry (components.yaml), thereby initializing a mepo repository.