Fix msg version type sent to cells RPC API

Regression fix from 6b16c8731c44e4a6c80b803f3e8afdd88386d577, cannot
build instances through cells.

The RPC dispatcher dislikes floats for version numbers.

bug 1190371

Change-Id: I18994ce8a524f88910cfe37c9b302296ce30102f
Merge "Fix msg version type sent to cells RPC API"