Apache Http Client 4.3 & various fixes

ok with Apache Http Client 4.3 https://github.com/lightbody/browsermob-proxy/issues/48
Fix dateTime fields for Har 1.2 spec https://github.com/lightbody/browsermob-proxy/issues/44
Deflate compression support
Implements TRY_AGAIN on DNS resolver
Fix Content-Length header and request content capture issue