Add scoped helpers environments from file-utils

Base generator now expose `.src` and `.dest` who're file-utils
environment scope as the sourceRoot and destinationRoot. This will allow
access to more file helpers method, and also more transparent process
for filtering, transpiling and validation (conflicter).
Merge pull request #378 from SBoudrias/yo.file

Add scoped helpers environments from file-utils
Prevent the end event from firing multiple times.
Merge pull request #402 from timrwood/single-end

Adding failing tests for end event firing multiple times when copying a file more than once.
Use `setImmediate` if available

Node.js 0.12 deprecate `process.nextTick`, so we use setImmediate when
available, fallback to process.nextTick otherwise.
Join `sourceRoot` and `destinationRoot` logic together

Logic for these method was split in base.js and actions.js. Now they're
merged back together.
Merge pull request #401 from Schoonology/master

Resolve destinationRoot in prepCopy.
Make sure destinationRoot is a resolved path

Using relative path may not always be consistent with the context.
Fix global modules detection

Now that env.js became `env/index.js`, global mobules are relatively 5
levels up from it.
Fixed cosmetic relative shown by conflicter due to #378
Merge pull request #413 from jdespatis/cosmetic-relative-path-log2

Fixed cosmetic relative shown by conflicter due to #378
0.14.0
Moved changelog to GitHub releases: https://github.com/yeoman/generator/releases
Make sure npm test command don't exit with non 0
Merge pull request #416 from SBoudrias/travis

Make sure npm test command don't exit with non 0
Update .npmignore
Merge pull request #419 from pwmckenna/patch-1

Update .npmignore
Added doc information clarifying options property used on hookFor method, relates to issue #214
Merge pull request #421 from ruyadorno/iss-214

Added doc information clarifying options property used on hookFor method...
Store independant Generators' meta data

This will help tools using the Yeoman Environment (like yo) to fetch
meta data from stored Generators without having to requiring each one.
(leading to performane improvement for them)