Use symbols for describes, consistently.
Added VCR gem
Obtaining an Aspera Transfer Config from MCS
Raises exception when MCS cannot generate the transfer configuration.

- namely when MCS does not recognize the asset ID,
- but also for any other error.
Removed large assets (used by upload) for a tiny one.

- these would appear in VCR cassettes (~16Megs) which seemed wasteful.
Added cassettes for remainder of tests
Creates an Asset Record in MCS
Factor out "Create Asset Record" into separate class.
CreateAssetRecordCommand prepares the POST body.

- removed VCR cassettes around "#create_asset_record" from MCS Connect.
MCS Connect uses CreateAssetRecordCommand to POST asset creates to MCS.
Moves 'access_token' attribute into 'connection_info' hash.

- fixed a bunch of tests that broke, depending on that attribute.
- replace WebMock with VCR for HTTP mocking.
Makes all 'describe' blocks the same style.
Removes unused mock fixtures (now supplied by VCR).
Uses single quotes for non-interpolated strings.
Removed #setup
Revved to 0.1.0