bidirectional synchronisation for pumpio

Disclaimer: This pull request contains not only changes to pumpio but also to twitter and statusnet - I did that work before we talked about branches.

**pumpio:**
There is now a working bidirectional sync with pumpio. Notes and comments are synced. Additionally likes are working bidirectional. it seems that there are no performance issues with this connector (in contrary to the facebook plugin)

Contacts are synced once a day.

It is even possible to directly address contacts from pumpio in a non public post. (they are added in the "bcc"-field) Additionally you can address pumpio contacts with "@username" and the pumpio post will add this address in the "to"-field of the posting - so that this post appears under "messages" in pumpio.

Own comments and likes are converted to the own contact - own notes are staying with the remote profile. In contrary to the Facebook plugin, the pumpio threads are separated from the friendica threads. I think this is less confusing for people in the two networks. In the other case, people from friendica would see my reply to a comment from pumpio - but not the comment I replied. (And vice versa)

The only thing that isn't synced, are the address lists. I'm not sure if that should be done uni- or bidirectional.

And you can't manage pumpio contacts. For this you still need the pumpio web interface.

**twitter:**
There were still problems with tweets that were too long. It seems as if Twitter calculates internally with 22 characters per link. The system now respects this. Additionally there is now a queuing so that a failed post (when Twitter isn't available) can be resumed.

**statusnet:**
I added some changes I did in the past at the Twitter plugin.