Add: number recognition, date recognition, field-names from first row, field names from supplied parameter

[simon-brooke]

Hi, this includes:

1. Optional recognition of numbers in data;
2. Optional recognition of dates/times in data;
3. Optional recognition of first row as field names;
4. Option to supply field names.

I've also upped the default Clojure version to 1.8, which may not suit you.

I'm seeing errors in one of your unit tests, perhaps because of the change to 1.8; and your benchmarks do not work for me, possibly for the same reason. I have not investigated either deeply.

I believe that the core algorithm of parse-csv-with-options could be written, probably using reduce, to consume less stack, and I may have a go at that when I have time.

I hope this is useful to you.