Group creation

# Changes #

### index.html ###
- Added moment.js for proper date formatting when creating new groups.
- Added groups.js - manages the creation of new groups.
- Added Parse.

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### groups.js ###
- **populateCollection()** will do a fetch for whatever collection you provide it. Abstracted this into a separate function simply to better enable testing. Also makes it reusable for any other collections.
- **generateRandomGroupID()** generates a random string using any characters specified in 'strCharsAvailable', at a length of the number specified in 'numGroupIDLength'.
- **createNewGroupID()** generates a new group ID, verifying it against all group IDs that have ever been created, until it makes one that's unique. Persists it to the Groups data class.

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### test.js ###
- Added test declarations for group creation.