Added upgrade section
Merge pull request #27 from cobracmder/myv7.0

Update README with upgrade section
Added "--networks|-w" argument to sdc-createmachine
Version bump (7.0.0-rc2) + Added changelog
Version bump (7.0.0-rc2), for real now
Added /my/networks right before we go for 7.0.0-rc3
Clarify that SDC_KEY_ID is a fingerprint not a name.