[Deprecation] remove schema v1 from the current version (and conversion support)

[vors]

To be able to move forward with #112, we need to remove schema v1 support from the tool.
Old versions of the tool still will be around, so if somebody didn't migrate yet, they can do that using an older version.

[vors]

@sankethka @jongeller are you ok with removing schema 1 from the tool?

[sankethka]

@vors Yeah I am fine. @jongeller @raien66 Any impact on migration?

[vors]

Removed from master, 0.7.6 is the latest version that supports the old schema.