Added image_filter_crop_offset
docs for "limit upstream tries"
Merge pull request #391 from cfsego/docs

pull request for limiting upstream tries
fix bug described in issue 384, which is about persistent connection in upstream_check_module
Merge pull request #392 from lilbedwin/upstream_check2

fix bug described in issue 384, which is about persistent connection in ...
Auto read nameserver from /etc/resolv.conf.
Merge pull request #390 from lifeibo/resolver

Auto read nameserver from /etc/resolv.conf.
https://github.com/alibaba/tengine/issues/368
Merge pull request #395 from taoyuanyuan/trim

trim module feature and bugfix (https://github.com/alibaba/tengine/issues/368)
improve the document of upstream check module
Merge pull request #396 from lilbedwin/upstream_check_doc

improve the document of upstream check module
"HEAD" method is recommended in upstream check module
Merge pull request #397 from lilbedwin/upstream_check_doc

"HEAD" method is recommended in upstream check module
Merge pull request #380 from Lax/feature/image_filter_crop_offset

Added image_filter_crop_offset
Striped the last linefeed in the resolver file

In CentOS 6.4, the interface gethostbyname can't parse the
nameserver string with extra linefeed.
Merge pull request #400 from yaoweibin/fix_resolver_linefeed

Striped the last linefeed in the resolver file