Lookup tree from cache-server
Add buildenvironment.py, cachekeycomputer.py from morph
Make Definitions into a class - seems unavoidable
Revert "Add buildenvironment.py, cachekeycomputer.py from morph"

This reverts commit e6db3c8609f82dc7dce8c8ae2dc4261b79472de2.
Merge branch 'definitions-as-class'