Updated namespace

[bizurkur]

This changes the primary namespace from org\bovigo\vfs to bovigo\vfs, but still maintains the org\bovigo\vfs namespace. Based this change on how Twig 2 did their namespace migration.

Closes #144

[allejo]

Thoughts on having our unit test namespace be bovigo\vfs\Tests instead of bovigo\vfs?

[bizurkur]

Thoughts on having our unit test namespace be bovigo\vfs\Tests instead of bovigo\vfs?

I do think that's how it should be, just wasn't sure if I should do it as part of this or not. I'm up for either part of this or a separate PR.

[allejo]

Both the unit test files and namespace are being touched in this PR, so I don't see the harm in doing it in this one.

[mikey179]

Thoughts on having our unit test namespace be bovigo\vfs\Tests instead of bovigo\vfs?

Not a fan of uppercase letters in namespace names, but if everyone agrees I'm fine with that.

[bizurkur]

Switched the test namespace to lowercase for consistency with everything else.

I generally write namespaces in StudlyCase (the same as a class name). Since they're all lowercase in the other files, it makes sense to keep it consistent.