… m3u.toString

…nting out the ENFLIST if the playlistType is not available, since it's optional

…if it's not there, it is assumed to be a VOD

…gram-date-time isnt available

…rging a playlist with a tail of another

… concat, also added concat ability

…tes(), m3u.findDateGaps() and m3u.insertPlaylistItemsAfter()

…enamed all new functions to be more explicit, also added test for m3u.mergeByDate()

… minor date slicing bug

```
{
	"message": "createM3U is not defined",
	"stack": "ReferenceError: createM3U is not defined\n    at M3U.mergeByDate (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/m3u8/m3u.js:190:80)\n    at /Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/lib/index.js:295:24\n    at tryCatchResolve (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/apply.js:46:23)\n    at callAndResolve (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/apply.js:30:12)\n    at callAndResolveNext (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/apply.js:40:4)\n    at tryCatchReject3 (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/makePromise.js:856:7)\n    at runContinuation3 (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/makePromise.js:814:4)\n    at Fulfilled.fold (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/makePromise.js:588:4)\n    at callAndResolve (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/apply.js:34:12)\n    at callAndResolveNext (/Users/akhoury/Perforce/akhoury_azizs-mac-mini_4287/speech/ramp/sites/m3u8-service/node_modules/when/lib/apply.js:40:4)"
}
```

…uence prop