Updated repository for easier first time setup.

I found it a bit challenging to set up the repository for the first time primarily due to outdated pip dependencies so I changed the requirements.txt to dependencies that worked for me and locked them to specific versions, git commits, or release tags.

In addition, the settings.example.py didn't fully reflect all the environment variables that were required by the scraper, parser, solr (ingester), and cwod_site so I added several variables and pointed CWOD_HOME to within the repository to ensure write access. 

The full list of changes can be seen below:

* Changed requirements.txt to lock git repo to commit/tag and upgrade outdated packages.
* Modified settings.example.py to better reflect settings required for the repository.
* Renamed capitolwords sqlite database to capitolwords.db.
* Modified README to have users check requirements.txt for python dependencies.
* Added data folder to gitignore to allow scraping data within the repository as set in settings.example.py.
* Added Makefile prevent comitting *.pyc files.
* Added check in parser to see if filename has "Pgnull" because parser currently fails on these files.
    * There are about 10 such files cumulatively in 1994 and 1995.