UK & Guinea plausibility/ncd list fixes

* UK's mobile ndc listing just happened to mostly work by luck (the 1.8
compatibility around splats)
* I originally based Guinea's around that code on the incorrect
assumption it was actually proper
* Also removed the `fixed(n)` cases from UK and Guinea for better
plausibility testing.

Interesting note: Ofcom (the UK body that administers phone number
assignment) has lists of all the allocated ndcs and their number lengths
(e.g. 4+5 vs 4+6 vs mixed) that are supposedly updated weekly. When
making the `fixed(n)` => `none` change for the UK, I ran a hacked
together test case that ran through every allocation and tested
plausibility. So now +44 numbers aren't considered plausible simply by
being 10 digits long (excluding country code). :D
be somewhat less strict about UK & Guinea plausibility, remove extra to_a
Merge pull request #198 from Emily/various_plausibility_fixes_for_uk_and_guinea

UK & Guinea plausibility/ndc list fixes