Use the right files for the version being built.

Use the correct root.json file to get TUF working.
Install pycrypto and others into the bundle so TUF can verify the data
correctly.
Move json version specifications to pkg/
Closes #6385, #6378, #6376.
Use newer Boost version and verify hash.

Use a specific OpenVPN version (2.3.5) so the build is normalized.

This closes #6296 and #6297.