Fix #159

Fix for #159
Permissions
Don't trust client ids

Doesn't throw errors if a random value is given e.g `/posts/djhfsjkdh`. This way if something invalid is provided as an `id` then no results are returned.
Have no title if there isn't a title set instead of undefined

Usually the title is `undefined`. This way it shows the URL instead if nothing is set in settings.
Show nothing instead of null

If these values aren't set they would be shown as `null`. They should just be `` (empty string)
Fix downvoting, cancelling upvoting & cancelling downvoting

Additionally removed the `(function() {})();` encapsulation since Meteor already adds this in since they started scoping files
Use _id instead of id
Use cursor to iterate lists of users
Fix subscription for spiderable
Use higher quality gravatar image
Merge pull request #160 from Tarangp/patch-2

Fix ability to delete posts
Merge pull request #161 from Tarangp/patch-3

Don't trust client ids
Merge pull request #162 from Tarangp/patch-4

Have no title if there isn't a title set instead of undefined
Merge pull request #163 from Tarangp/patch-5

Show nothing instead of null
Merge pull request #164 from Tarangp/patch-6

Fix downvoting, cancelling upvoting & cancelling downvoting
fixing updateScore syntax
Merge pull request #166 from Tarangp/patch-7

Use cursor to iterate lists of users
Merge pull request #167 from ryw/fix-subscription-for-spiderable

Fix subscription for spiderable
Merge pull request #168 from ryw/higher-def-image

Use higher quality gravatar image
syntax fix