Also fix up various things that rubocop called out, though not
everything. Mostly whitespace fixes, changing double-quotes to single if
double wasn't required, changing to use ruby 2.x hash syntax where
possible, etc. While tests don't run, they are no more broken than
before (at least, as far as I can tell).
Calling #all fails with the error: `Excon::Error::Socket: 25:28: FATAL: Document is empty (Nokogiri::XML::SyntaxError)`. This was because of the parser not handling nil creationDate values:
```
when 'creationDate'
@image[name] = Time.parse(value)
```
This commit ensures nil `creationDate` fields are not parsed.
