Fix a bug in R.skip

Calling `R.skip(n, list)` for `n >= list.length` would result in an error being thrown. Instead,
this commit causes an empty array to be returned.
Merge pull request #340 from markprzepiora/fix-skip-bug

Fix a bug in R.skip
Skipping extra call to _slice when called with one arg
Add missing test module

The `is` test file was not included in test/index.html, and so its tests were
not run. This commit adds it.
package.json: alphabetize dependencies
Merge pull request #342 from davidchambers/dependencies

package.json: alphabetize dependencies
Merge pull request #341 from markprzepiora/run-is-test

Add missing test module
some little doc fixes
Add support for headless testing using Testem

The test suite can now be run by installing testem globally and running
"testem" (or "testem -l phantomjs" if you have phantomjs installed to run tests
headlessly).

If you don't want to (or cannot) install testem globally, you can run
"./node_modules/bin/testem" instead.

These commits:
- Replace inline require shim with a file
- Add testem and configuration
- Add section to the README describing how to run tests
Merge pull request #343 from markprzepiora/testem

Add support for headless testing using Testem
simplify dependencies for browser tests
Merge pull request #345 from davidchambers/browser-tests

simplify dependencies for browser tests
Revert "simplify dependencies for browser tests"
Merge pull request #346 from CrossEye/revert-345-browser-tests

Revert "simplify dependencies for browser tests"