Shopify 422 Error Logging, filtering improvements, ignore_files configuration support and theme_id support

• Filters can now be initialized with both the contents of files and from an array of patterns (fixes #12)
• ignore_files wasn't being properly detected and these fields weren't being added to the filters. This meant that .git directories would be included in filters and would causes several wasted API requests that would be rejected by Shopify
• Updates version.go and adds a wrapper around log.Fatal to provide version information.