Allow comma-delimited and nested lists for rem()
Fix typo
Only convert units if use-px-fallback is set
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.
Merge branch 'master' into list-rems

* master:
  Bump version to 1.0.0.alpha.18.
  Bump version to 1.0.0.alpha.17.
  Bump Sass version dependency.
  Had this str-index function backwards.
  Handle checking for the stylesheet root by defining a custom function.
  Deprecate random because it's provided by Sass now.
  Bump import-once version.
  Changed gradient direction from to bottom to to top (... hah)
  Fixed syntax for linear-gradient
Merge pull request #1523 from chriseppstein/list-rems

Allow comma-delimited and nested lists for rem()
Rem always outputs rem values
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.