Fsdb

Changelog:
- Included docs in source package
- bugfix: all files in the source package had executable bit setted. ( thanks boyska )

Changelog
- bugfix: the dumped configuration file was containing only user configured parameters. Instead we are interested in keeping always at least the minimum configuration on the fsdb root path for further reuse.

Changelog:
- In version v1.0 the configuration parameter `deep` has been substituted with `depth`. The deep parameter stored in old configuration files was ignored. Now old configuration files are supported as well.
- Fix octal integer handling:
In the previous versions we use to represent an octal number with a 0-prefix. Since python3 has migrated to 0o-prefix rapresentation, we decided to switch to our custom simple representation: the octal number should be a simple 3 digits number.
So for example if in the previous version you were using `0660` as value for the `fmode` parameter, now you can also use `660`.

In any case we keep support for 0-prefix and 0o-prefix as well, thus you don't need to change
anything before the upgrade.
- Added tests to source package (thanks boyska )

Changelog:
- Bugfix: Since version v1.0 the `__getitem__` function was bugged on pyhton 2. The problem was about string type check, now is solved.

Changelog
- added python 3 support [`3.3`, `3.4`, `3.5`]
- added python 2.6 support
- configuration parameters `deep`, now it's called in the right way: `depth`.
This means that you need to modify your code in order to use this new version.
Since there are no improvement in the code except for the support to python 3,
you can also stay with the `v0.3.3`

Changelog:
- tests refractoring
- test about file permission was a false positive
- added function to calculate fsdb instance size ( disk space )
- improved insertion code