refine HOSTSFiter
refine HostsFilter
drop stripssl_handler_filter
add sticky_filter
use tls default
find GoAgent CA fingerprint by sha1
bugfix for mock 500/502/503
refine crypt cert handling
bugfix: no response body for HEAD, status 204, 304
Merge pull request #8 from v3aqb/patch-3

bug fix: no response body for HEAD, status 204, 304
Merge branch '3.0' of https://github.com/goagent/goagent into 3.0
bugfix
bugfix for dns servers
refine create_tcp_connection
add handle_urlfetch_error
bugfix for over qouta
bugfix for urlfetch
revert to sslv23
bugfix for urlfetch
bugfix soundcloud