Two minor tweaks for precision.

* policy.md
  (maximizing-community-involvement-and-reuse): State more
    precisely the licensing implications for joint works.
  (distribution-of-code): Rephrase to affirm that all open
    source licenses permit internal use without redistribution,
    rather than implying that only some OSS licenses do.
Merge pull request #15 from OpenTechStrategies/master

Two minor tweaks for precision.