Identify ourselves as rest-client and also include system architecture
and ruby / ruby engine version information.
For example:
User-Agent: rest-client/1.7.2 (linux-gnu x86_64) ruby/1.9.3p550
User-Agent: rest-client/1.7.2 (linux x86_64) jruby/1.7.9 (1.9.3p392)
This is helpful for users wanting to apply their own custom certificate
verification logic. Add warnings by default if it is used on OS X or
jruby, which may not support the functionality as expected.
Apple patches OpenSSL to always fall back on the system CA store, so
the integration tests that expect SSL cert failures have never worked on
OS X. Disable them since I can't think of a workaround :-(.
TODO: add some integration tests on certificates that won't be in any
system CA store.
