Unbreak LICENSE link in README

The LICENSE link in README specified the path compass/blob/stable/, but the GitHub MarkDown renderer automatically makes links relative to <repository>/blob/<branch>. I removed the path, and the link now works.
English-language correction
Changed two types of quotes to single quotes

Changed two types of quotes in the same line to single quotes only.
Change Erics name
Merge pull request #1577 from chriseppstein/eric-suzanne

Eric Suzanne
Update copyright years

Keeping these years up-to-date helps the project feel more active and
gives people more confidence that it is still maintained and will still
work.
Merge pull request #1588 from lencioni/copyright

Update copyright years
Explain how to use import-once with sass cli.
Remove old beta changelogs to avoid confusion.

Closes #1567
Merge pull request #1528 from lolmaus/patch-1

Minor README corrections
Merge pull request #1526 from btmills/master

Unbreak LICENSE link in README
Depend on and/or allow Sass 3.3
Add some files to be ignored.
Fix bug when import-once used with sass-globbing.

Adds unit tests for import-once functionality.

Import once importer should allow for importers that accept additional arguments to their APIs.
Closes #1529.
Allow compass to be used against sass 3.4 alphas.
Bump version of true to allow Sass 3.4 alphas.
change the authored color format in tests so that it matches the old output format.
Sass doesn't set the sourcemap filename option for you.

Closes #1574.
Fix issue where imports passed to the cli weren't picked up if the config had additional_import_paths.
Make inherited configuration arrays accumulate.

Keeps the sprite_load_path semantics such that they clobber so
that the tests pass there.