Fix sourceMappingURL

Broken from 04dd6f2268

Simple fix to cast the const pointer to a non-const pointer. String
seems to still need to be copied.
Merge pull request #241 from chrisirhc/feature/fix-sourcemap-url

Fix sourceMappingURL
Added link to meteor plugin
Adding Mimosa to README integrations section
Merge pull request #247 from dbashford/patch-1

Adding Mimosa to README integrations section
Update libsass to 1122ead208 (2014-03-04)
Merge pull request #255 from keithamus/update-libsass

Update libsass to 1122ead208 (2014-03-04)
0.8.2
0.8.3
Adjusted note on outputStyle option

Closes #258
Remove line regarding copying built binary and adding note on libsass differences
Add Gitter badge to README
Merge pull request #265 from andrew/readme-build-update

README tweaks
Add list of maintainers to README
Change to actual list so each maintainer appears on a new line
Update Contributors copy
Merge pull request #266 from andrew/add-maintainers

Add list of maintainers to README
Dependencies bump, all tests passing
Further dep. version bumps as david-dm was giving false version numbers
Clarify the libsass reporting workflow

- Update when API issues should be created here
- Dropped the word "recent" as that term will get dated quickly.
- Use the libsass markdown anchor throughout.