Set endpoint pool chunk size to 10MB.

Vastly improves efficiency of startup.
Review markup.

We considered being more precise and working out how much space is
actually needed, but a 10MB increment means an expected waste of
5MB for the whole process, which is negligible for our application.
Hence this straightforward approach is fine.
Merge pull request #4 from Metaswitch/improve-startup-efficiency

[Reviewer: Mike] Set endpoint pool chunk size to 10MB.