Rewrite PostFrames frames data parser logic.

Now with less regexp.
Minor refactor.
Modernize PostFrames queries.
Explicit tag xml builder.
Use hash rocket syntax everywhere.
Double quotes everywhere.

Using rubocop's auto-correct.
Rubocop enforce trailing blank lines with final_newline.
Purge out trailing whitespace.
Replace deprecated File.exists? with File.exist?
*_filter => *_action.
Replace character literal with string literal.
Replace Hash#has_key? with Hash#key?

Informally deprecated? https://github.com/bbatsov/rubocop/issues/791
Remove extraneous blank lines.
Negate with `!` instead of `not`.

Leveraged rubocop auto-correct.
Check nil with `.nil?` instead of `== nil`.
Remove usage of not which couldn't be auto-corrected.
Simpler not-nil check.
Fix all space-related styling.

Courtesy rubocop.
Remove useless trailing semicolon.
Remove extra parentheses.