Update keepValidPages to include a filter on 200 OK.

[ruebot]

GitHub issue(s): #359

What does this Pull Request do?

• Add status code filter to keepValidPages
• Add MimeTypeTika to valid pages DF
• Update tests since we filter more and better now 😄
• Resolves Enhance keepValidPages  #359

How should this be tested?

• TravisCI should take care of it, but sanity testing would be good if you have the time @ianmilligan1

Additional Notes:

• I'll look at the documentation, and see if anything needs to be updated

[codecov]

Codecov Report

Merging #360 into master will decrease coverage by <.01%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master     #360      +/-   ##
==========================================
- Coverage   75.93%   75.93%   -0.01%     
==========================================
  Files          39       39              
  Lines        1388     1392       +4     
  Branches      266      267       +1     
==========================================
+ Hits         1054     1057       +3     
  Misses        218      218              
- Partials      116      117       +1

[ianmilligan1]

Built and tested locally - all checks out. For fun, I ran a diff on the file using this branch vs. the 0.18.0 release. Here are the things that no longer appear in the plain text output.

If you keep scrolling it's this stuff over and over again, so I'd say this is a major enhancement. Great stuff, @ruebot !