Add -h option to print documentation on gif2gfy's usage
Changed README.md's goals section further
Change brief options to long options for better readability
Switch to is_null() for ffmpeg availability check
Create check for ffprobe and create test for bundled ffmpeg and ffprobe instead of hardcoding them in
Add -c option to gif2gfy for specifying alternative background colors
Move -h in gif2gfy into its own section in help page
Move -h in gif2gfy into its own section in help page