invenio 1.9999.1.dev

* dynamic PEP440 version (_à la_ django).
* invenio 1.9999.1 dev.
* **NB:** `git commit --amend` doesn't change the `Date` attribute. You have to do so instead: `git commit --amend --date="$(date -R)"`

```console
$ git log -1
commit 341142ac0ccb826abaaded2c078415e3fe9260b5
Author: Yoan Blanc <yoan.blanc@cern.ch>
Date:   Tue Jul 22 14:25:52 2014 +0200

...
$ python setup.py --fullname
Invenio-1.9999.1.dev20140725123932
$ python -c "from verlib import NormalizedVersion as V; print(V('1.9999.1.dev20140725123932'))"
1.9999.1.dev20140725123932
$ nosetests --with-doctest invenio/version.py
.
----------------------------------------------------------------------
Ran 1 test in 0.003s

OK
```

### Discussion

**EDIT:** the Option 1 is the one picked here.

The implemented model is not very flexible, as it doesn't allow such anything but _alpha_ to be in dev.
```
2.0.dev2014...
2.0b0.dev2014...
2.0.post0.dev2014...
```

We could either: Option 1, simplify it to have only dev/non-dev, e.g. the fourth argument being that.

```python
version = (2, 0, 0)  # 2.0
version = (2, 0, 1, 'dev')  # 2.0.1.dev2014...
```

Or, Option 2, let `dev` be a fifth or sixth argument for the full blown PEP440 possibilities.
```python
version = (2, 0, 0, 'final')  # 2.0
version = (2, 0, 1, 'alpha', 'dev') # 2.0.1a0.dev2014...
version = (2, 0, 1, 'alpha')  # 2.0.1a0
version = (2, 0, 1, 'alpha', 1)  # 2.0.1a1
version = (2, 0, 1, 'beta', 1, 'dev')  # 2.0.1b1.dev2014...
version = (2, 0, 1, 'rc', 1)  # 2.0.1rc1
version = (2, 0, 1, 'final', 'dev')  # 2.0.1.dev2014...
version = (2, 0, 1, 'final')  # 2.0.1
version = (2, 0, 1, 'final', 1, 'dev')  # 2.0.1.post1.dev2014...
# ...
```

I'd go with option 1 to keep things super simple and make the release process easy enough.