Alpha0.5

As suggested in #9, I am recommending that alpha0.5 be merged into master. A summary of the changes between alpha0.5 and master is below. Comments, criticisms, and concerns are welcome.

Alpha0.5:

-  provides a declarative syntax for reading and writing properties. Described in the [documentation](http://pyopenworm.readthedocs.org/en/alpha0.5/#pyopenworm).
-  offers an extensible means of defining [new objects](http://pyopenworm.readthedocs.org/en/alpha0.5/making_dataObjects.html) using normal Python classes. New objects and types of objects can be added to shared databases while still being accessible to library versions which lack definition of these additional classes and objects.
-  features [updated documentation](http://pyopenworm.readthedocs.org/en/alpha0.5/making_dataObjects.html) on the changes.
-  enables higher-order statements to be made about the [properties](http://pyopenworm.readthedocs.org/en/alpha0.5/index.html#PyOpenWorm.dataObject.Property) of an object and the relationships between objects.
-  comes with [initial data](https://github.com/mwatts15/OpenWormData) based on pre-existing data sources
-  includes unit tests which cover the core functionality