Add a pending spec for #245.

It's a bug in webmock (bblimke/webmock#246). This
spec will help prevent future regressions.

Closes #245.
Fix issue with `around_http_request` when using multiple threads.

Fibers cannot be shared across threads, and you would get an error
when using this feature with threads:

FiberError: fiber called across threads

Actually, we were rescuing FiberError and transforming it into an even more confusing error:

Your around_http_request hook declared at <location> must call #proceed on the yielded request but did not.

Note that VCR is not thread safe (see #200) but this brings it a bit closer.

Fixes #257.
Merge pull request #258 from vcr/fix_around_http_request_hook

Fix issue with `around_http_request` when using multiple threads.
Changelog entry for #258.

[ci skip]
[Issue 237] Make configure_rspec_metadata! effectively idempotent
Need to initialize instance variable.
add special jruby handling

provided by aruba

update deps
conditional aruba java deps
Merge pull request #264 from plukevdh/jruby-stability

Jruby stability
Changes source from :rubygems to https://rubygems.org to remove warning.
Raises webmock version to 1.10
Merge pull request #268 from johanneswuerbach/rubygems-warning

Changes source from :rubygems to https://rubygems.org to remove warning.
Build against ruby 2.0.0.

(but allow failure for now until we get it passing)
Merge pull request #269 from johanneswuerbach/webmock-1.10

Raises webmock version to 1.10
Add changelog entry for #269.

[ci skip]
Update lots of gems.

This updates all gems except excon, faraday and webmock.
Initially, I updated those gems, too, but they caused
test failures.  I'll be updating those separately.
Update Faraday.

Faraday 0.8.6 includes a User-Agent request header by default.
Force encoding to US-ASCII since ruby 2.0.0 defaults to UTF-8
Ruby 1.8 doesn't have force_encoding.
Fix default headers for Ruby 2.0