Clean up Apache and Nginx integration tests.

- Make the tests as language-independent as possible so that the same set
  of tests can be run for each supported language.
- Fix some brittlenesses in the tests.
- Begin getting rid of the dependency on Rails 2.
Fix newly discovered ApplicationPool bugs which could cause queued requests not to be processed when they should be, or which could cause too many processes to be spawned.
Fix Nginx page caching support when using the new sub-URI deployment instructions
Update documentation IDmaps
Rename the 'passenger-config info' command to 'passenger-config about'
Make the Ruby 1.8 Travis tests use an older RubyGems version
Fix a Debian packaging bug
Fix message indenting in native_support.rb
Change some more 'require' calls to 'PhusionPassenger.require_passenger_lib'
Fix a problem that prevents the Apache 2 integration tests from running in natively packaged mode
Make the Ruby native extension check whether it's loaded against the right Ruby version, to prevent problems when people upgrade Ruby without recompiling their native extensions.
Disable C++11 compiler flags on FreeBSD because of possible Clang bugs. See http://llvm.org/bugs/show_bug.cgi?id=18310
Ignore EPIPE and ECONNRESET when the Apache module is forwarding the HTTP body to the HelperAgent using in-memory buffering
Fix Nginx integration test failures
Fallback from accept4() to accept() upon getting EINVAL as error. This error code is returned by FreeBSD