add authorLogo, authorBio, authorTwitter, creationTime, category fields

Adding all the new fields we want to have.
Take the "@" off of authorTwitter if found, so it's consistently present or not
When validating activator.properties fields, allow length == limit

The limits were all arbitrary anyway, so this didn't really matter.
But about to check twitter handle length which is 15 precisely.
Add validation of twitter usernames in authorTwitter field
add setCategory to StorageRestOps
add a val with a list of all hardcoded categories
Merge pull request #24 from typesafehub/wip/havocp-extra-metadata

Adding extra metadata fields