Add Futurepool arg to ServiceToClient

If you want to have your Array[Byte] -> Thrift
deserialization to happen on a FuturePool, maybe
because it is very large or nested or something,
you can now pass in a FuturePool argument.

The existing 2-arg constructor was preserved so that
Thrift.newIface continues to work.
Clean up some reStructuredText formatting.

This primarily involves escaping[1] the pluralizing "s" character when
it immediately follows an inline literal.

Also, fix the Thrift IDL link (no trailing backslash allowed).

[1] http://docutils.sourceforge.net/docs/user/rst/quickref.html#escaping
Merge pull request #47 from slackhappy/johng_futurepooldeser

Add Futurepool arg to ServiceToClient
Merge pull request #51 from jparise/docs-cleanup

Clean up some reStructuredText formatting.