[Review] Request from 'KalabiYau' @ 'SUSE/connect/review_140716_add_proxy_support_to_client'

Please review the following changes:
  * 85b1c2b fix bnc#885957. Now http connection reads curlrc for proxy credentials
  * b54eee5 Inject proxy credentials from curlrc
  * 1dcfa86 Create basic curlrc class to operate on curlrc file