Isolated extension environment

Isolated the extension environment and refactored commands: init,
generate, compile, install.
The extension project can be located anywhere on disk.
The init command takes a parameter <namespace>
The generate, compile and install commands must be ran within the
folder of the project.
Fix travis.yml

Fix travis.yml
Fix unit tests

Fix unit tests
Use basename(getcwd()) as default namespace

Use basename(getcwd()) as default namespace
Fix param check

Fix param check
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Library/Compiler.php
Restored install process

Restored original install process whereby the ZEPHIRDIR environment
variable is used to find zephir.
Additionally, install now takes a -c parameter to copy zephir to
/usr/local/bin if prefered. Also, zephir-parser is no longer copied to
/usr/local/bin with zephir
Merge pull request #18 from mobli/master

Isolated extension environment