PATH variables often splitted by : in unix

In unix PATH variable contains `:` as delimeter, and some scripts
in .bashrc can append empty parts to it.

Related with #444
Merge pull request #445 from floatdrop/fix-node-path-parsing

PATH variables splitted by : in unix and can contain ::
New prerelease
Implement new Generator.extend inheritance method
Merge pull request #446 from SBoudrias/inheritance

Implement new Generator.extend inheritance method
Create .jscs.json

https://github.com/mdevils/node-jscs
Find all node_modules directories, not only nearest to root

Findup searches for the first `node_modules` directory in cwd and
it's ancestors, but what if our generators in `~/node_modules`,
and we calling generator in directory, that has `node_modules`?
Right - `yo` will think, that you have 0 generators.

Closes #440
Merge branch 'floatdrop-findup-all-issue-440'
Start fixing style guide issues
Fix user module unit test
Apply style guide
Reduce files scope of #directory() test (Fix #438)
First stab at gulp
Convert benchmarks to matcha
Remove benchmark.js from deps as we now use matcha
Add global var to pass jshint on benchmark
Simplify methods with the new Generator.extend inheritance
Update dependencies and fix inheritance test
Release version 0.15.0
add helpers assert[No]FileContent, assertNoFile and tests
refactor some other helpers