Create initial tests for article results (#16)

Provides automated testing of the article scraper using Instapaper configuration files.

Reading and internal representation of the configuration files is provided by the `saulify.sitespec` module. Site configuration files are stored in the `sitespecs` directory (as opposed to `tests`, as they may also contain article extraction rules that are not specific to testing).

Run the test suite by typing
    
    python runreport.py

in the root directory of the project. The output is a series of JSON dictionaries (one per line) detailing the results of each test.
I agree. The line where we generate the article html from markdown which was generated from the cleaned html also looks odd to me. For the purpose of this pull request (and without being sure of what the author's intentions were) I just wanted to extract the method without changing any of its functionality, but it should be revisited.