* adds kopia pkg to handle integration (#25)
internal/kopia will be used to abstract all kopia integration in a
central location.
* defer blob.Storage closure in kopia
blob.Storage objects must get closed at the end of their usage.
This currently isn't getting called.
* introduce repository api scaffold with s3 (#6)
introduces the public repository package in /pkg, with a
skeleton implementation for generating the s3 provider config
and boilerplate for where that usage gets centralized.
* condense init/connect to single action
A double-pass NewRepo() && Connect() allows Repository structs
to exist independent guarantees that their usage will be successful.
This hides the struct generation within the Connect and Initialize
funcs so that the construction and guarantees can occur as
a single process.
Now reflects the fact that this will be cloned from github. Also place
in source directory so that all packages in the project don't need to be
`src/foo`.
