Merge tag 'sparks-1.3.7' into develop

1.3.7
Make deactivate prefixes masked on the shell level, else they pollute the python output and sparks fail to detect the platform.
Allow `fab -H … <task> -- --verbose` to make the `RemoteConfiguration` detection verbose without having to patch the code.
PIP2/PIP3 enhancements in my personal fabfile (which is in sparks, anyway).
Make the PIP3 detection actually work.
Merge branch 'release/1.4'