Fix for boards.allCategories returning out of order
Updating npm package to 0.5.6.
Fixed old posts shown as last updated thread in boards

Fixed an issue where an old imported post with an obsolete created_at
property could end up as being shown as the last updated thread on the
homepage. The fix basically involves checking the board's current last
updated at timestamp and seeing if the incoming post's created_at
property is equal to or larger than that.
User Views

Added the user_views metadata to the users model. This new metadata is
basically an object that just keeps track of all the threads a
particular user has view and at which point in time that user viewed
said thread.

There are two new methods, getUserViews and putUserViews. getUserViews
takes in a userId and retrieve that object that contains all the user
views for that id.

The putUserViews takes in a userId and a userViewsArray object. The id
is used to pull the correct userViews object and the array of user views
is added/updated to that object. The put call has a lock around it to
prevent any concurrent calls from overwriting data.
Refactor

- Use of assignment of var self = this should be only used when needed.
- Moved empty array return to module scope instead of creation on every
  return.
Encoding for bytewise extracted to helper

- modularize db.js to db/index.js
- config.js now takes in consideration of process.cwd() for default db
  location
- posts db/model now uses the new helper extracted version of
  encodeIntHex for bytewise encoding.
Making sure that epoch.db is in the correct place.

- epoch.db should be path.join'ed.
allow created_at field in user validation
implement import view_count for threads
workaround for category updates via the importer