Integrate IAAO Data Quality Standard appendices

[dfsnow]

We should add functions to replicate the methods outlined in the IAAO Data Quality Standard. Specifically, we can likely add functions for:

• Appendix F. Sold and Unsold
• Appendix I. Edge Case Identification
• Appendix J. General Data Quality Score
• Appendix K. Impact Identification

Ask @dfsnow for a copy of the document.

When this issue is closed, notify Travis.