Including ProxyManager in frameworks tracked for zend parity

ProxyManager is a dependency of ZF2 and SF2 that is doing some very tricky code generation, as well as dealing with unset properties, serialization, cloning, etc.

It is currently not on par with HHVM, but reflection and core features of HHVM cause huge fluctuations in test success rate.

I'm already testing the repo against HHVM nightly (allowed failure on travis, for now), and am tracking compat at Ocramius/ProxyManager#127, but a comparison view on http://www.hhvm.com/frameworks/ would help me greatly in identifying/reporting regressions.