README updated with pg_repack 1.1/1.2 differences
Docs cleanup before releasing 1.2
Remove generated blank lines from legacy .sql file

They appear cause portability problems.
Fixes issue #12.
Bumping version to 1.2.0-beta1

Remember to put back the release status to 'stable' before releasing
the final version.

I hope I got the right version number format for PGXN...