Don't crash when printing an error from COPY #minor

When importing the header of my csv, I saw:

```
Executing command: COPY artist_test1 (id, name, auction_lots_count, location) FROM 's3://my-bucket/my.csv' CREDENTIALS 'aws_access_key_id=REDACTED;aws_secret_access_key=REDACTED' CSV
/Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/stl_load_error.rb:66:in `from_pg_results_row': undefined method `parse' for Time:Class (NoMethodError)
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/stl_load_error_fetcher.rb:9:in `block in fetch_errors'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/stl_load_error_fetcher.rb:8:in `each'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/stl_load_error_fetcher.rb:8:in `fetch_errors'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/copy_command.rb:46:in `rescue in execute'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/copy_command.rb:40:in `execute'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/boot.rb:23:in `boot'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/flare-up-0.7/lib/flare_up/cli.rb:41:in `copy'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
	from /Users/artsyinc/.rvm/gems/ruby-2.1.0@flare/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
	from ./bin/flare-up:5:in `<main>'
```

This PR changes the error to print correctly:

```
Executing command: COPY artist_test1 (id, name, auction_lots_count, location) FROM 's3://my-bucket/my.csv' CREDENTIALS 'aws_access_key_id=REDACTED;aws_secret_access_key=REDACTED' CSV
There was an error processing the COPY command.  Displaying the last (1) errors.
START : 2014-11-13 20:23:56 UTC (2014-11-13 13:23:56 UTC PST)
REASON: Invalid digit, Value 'a', Pos 0, Type: Integer
LINE  : 1
POS   : 8
TYPE  : int4
LINE  : id,name,auction_lots_count,location
```