Add component for queuing messages.

All incomming messages are kept in memory. As soon as the queu reaches the
pre-configured size of 100 messages, the current list of messages is send.

You can reconfigure the queu size of the component by sending a message to
the `size` input port of this component. If the incomming data is not a
positive integer, an error message will be send to the `err` out port of this
component.
Create test skeleton.
Merge pull request #6 from marijn/feature/queu-component

[WIP] Add component for queuing messages.