Infer values dtype from python data type

When creating an odML `Value` with `data` parameter, the library will try to infer the odML dtype of the value from the python data type. Further the constructor of property now creates a value with the `data` parameter instead of the `value` parameter.
This makes it easier to create `Properties` with the correct dtype on their values.

Example:
```python
p = Property("some int", 10.1)
p.value.dtype   # -> 'float'

p = Property("some int", date(2001, 12, 30))
p.value.dtype   # -> 'date'
``` 

This should work for bool, int, float, string, date, time and timestamp.

Other small changes:

- Optional support for setuptools
- Additional files in gitignore
- Other changes from lzehl's pull request