Reviewer Ellie: Tel URIs part II

Hi Ellie. Please can you review the changes for the remainder of my sprout tel URIs work? This includes the following changes:

* Route failed ENUM lookups to the BGCF rather than rejecting them. This also means doing a default translation when we don't have an ENUM server configured. This includes rejigging the UTs.
* Extracting a list of aliases from the Service Profile and pumping them back through to scscfsproutlet.cpp. This includes hssconnection UTs. This work was needed for the next section.
* Adding a second PAI header when required. This includes full UTs in scscf_test.cpp.

I haven't done any live testing, the UTs are adequate.

Let me know if you have any questions.

Thanks,
Graeme 
I kind of agree, but it now means adding a default entry to the bgcf which breaks a ton of other tests, and the flow is the same as the next test. I've already spent a few hours trying to get it working and i don't think it's important enough to justify holding back this pull request, so i'll put it on my to do list.