2.0 -> 2.
Merge pull request #366 from dcsommer/master

Restore GOAWAY
Reverting collateral edit from #366.
Reorder DATA frame padding flags.
Merge pull request #367 from jpinner/reorder_padding_flags

Reorder DATA frame padding flags.
Merge branch 'master' of https://github.com/http2/http2-spec
Minor editorial changes to HPACK.
Typo correction.
Merge pull request #368 from jpinner/hpack_updates

Minor editorial changes to HPACK.
Tries to improve Jeff's proposal.
Minor corrections.
Update definition of SETTINGS_HEADER_TABLE_SIZE.

Allows the effective size of the header table to be changed by the
encoder inside the header compression data.
Describe handling of invalid values for SETTINGS_ENABLE_PUSH.
Clean up some reference links.
Fixing push cacheability section to match other push descriptions.  Closes #370.
refine approach to hop-by-hop headers; addresses #21.
HPACK is standards-track, not informational
Merge pull request #371 from jpinner/more_hpack_ed_updates

Clean up some reference links.
Minor formatting fixes.
Adds Acknowledgements.