[Issue #47] CLI naming clash when run under Bundler

Fixes a load_path naming clash when `bin/approvals` is run under
Bundler.

Looks like it's picking up a different `CLI` lib from Thor instead of
the `Approvals::CLI`.

Verified by renaming `cli.rb` to something else & updating the `require`
statement to avoid naming clash.
Merge pull request #48 from zph/issue_47/fix_cli_naming_clash_under_bundler

[Issue #47] CLI naming clash when run under Bundler
Bump version
Switch to Nokogiri::HTML for html writer

By switching to the HTML parser from the XML parser, we can better handle malformed html documents and save out something that at least marginally resembles the input HTML.
Merge pull request #46 from hotgazpacho/html-writer
Bump version