Gemfile: Instruct nokogiri to use the system version of libxml.

This shrinks the bundle size by about 100MB.

https://github.com/sparklemotion/nokogiri/issues/952
Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Quirks: Work around em Client 5.x

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Move request/response logging into an ensure block.

This ensures logging if an HTTP status is thrown and ensures the
correct HTTP status is returned in all cases.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Add an HTTP request headers debugging knob.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>