update docs

Add custom packages first.

update-server-info only needs to be called by "medusa update"

enable mirroring of non-github repos; non-packagist is a different is…

…sue; .phar generation was incomplete (skipped some new vendor dependencies)

Generate updated medusa.phar (for internal use)

The force flag is needed when updating a mirror.

Merge pull request #5 from cordoval/master

avoid warning for when property name on repository does not exist