Add exception for incompatible operator in search

e.g., using ">" with a string or "includes" with a number. There are
SOME cases that this breaks, such as when the user wants to find samples
where a varchar column includes "7" (or some other number)
Add handling of exception to search

Also fix minor typo in another file
Add check for argument/operator disagreement
Detect column types needed

This breaks if a column is referenced as both a numerical and a string column
e.g., a query containing "ph < 5 or ph = high"
Fix Pep8 Fail
Fix bug with column selection
Fix expected text in tests
Merge pull request #252 from adamrp/issue-229

Issue 229