Rewrote invalid CSV test, some small refactoring

test_does_not_parse_invalid_csv now looks to match "InvalidFormatError" in
Dinodex's output

Added magic number weight (2000) to dino_config as BIG_DINO_WEIGHT_THRESHOLD

Moved the operation to turn CSV files into hashes back into dinodex.rb
(out of the formatter)
Refactor identify_format to return a Formatter obj

As a result, removed Formatter.format, and instead assigned the returned
Formatter object to a variable 'formatter' such that we can call
formatter.format(...) instead of Formatter.format(...)
Redid test_finds_multiple_search_criteria

New case is slightly more interesting than the last, as the first two
finds both return more than one dino.
Refactored match methods to use respond_to

Occurs in matches? and in matches_weight?