Upgrade SimpleWebServer to version 2.1.1

[withsmilo]

Currently Clipper uses SimpleWebServer(Oct 25, 2016) for http serving.
We need to upgrade this module to resolve some bugs and support keep-alive connection.
So we applied all patches except of some to reach version 2.1.1 (May 27, 2017).
Diff between SimpleWebServer v2.1.1(left). and SimpleWebServer(right) in this PR is here.

• applied patch list

  • Nov 7, 2016: Fixes #82: wrong reset method called in ::start
  • Nov 10, 2016: Fixed crash if server instance gets deleted after the call to io_serv
  • Nov 23, 2016: Fixes #86: can now set timeout on client requests
  • Nov 23, 2016: Minor timeout source cleanups
  • Nov 23: 2016: Simplified Server::parse_request
  • Dec 4, 2016: string::substr comparisons replaced by string::compare
  • Dec 13, 2016: compile clean with gcc 4.6.3
  • Dec 19, 2016: Added client verification when a verify file is passed to Server<HTTP
  • Dec 19, 2016: Added error reporting through on_error std::function
  • Dec 19, 2016: Minor cleanup
  • Dec 19, 2016: Minor cleanup
  • Dec 29, 2016: Cleanup of server-constructors. Previous constructors have been marked
  • Dec 29, 2016: Bugfix for last commit: config.timeout_content now correctly set in old constructor
  • Dec 30, 2016: Fixed DEPRECATED macro in cases where it is already defined
  • Dec 31, 2016: Case insensitive header cleanup. Also cleanup and additions to parse_test
  • Jan 1, 2017: Added on_upgrade for cases where one wants to handle connection upgrades
  • Jan 11, 2017: Fixed Boost.Regex workaround in regex_orderable. Fixes #100
  • Jan 24, 2017: Possible implementation for fixing #106
  • Jan 24, 2017: Renamed close_connection_after_send to close_connection_after_response
  • Feb 5, 2017: Added query string parsing and member to request
  • Feb 5, 2017: Travis CI build failed
  • Feb 14, 2017: remove locale dependent stof()
  • Feb 27, 2017: If query string is present then cut it from the reqeust path so find
  • May 6, 2017: Added support for request header Connection: keep-alive (see #123)
  • May 27, 2017: Finished query string parsing implementation (PR #109)
  • May 27, 2017: Fixed g++ error in Server::Request::parse_query_string

• excluded patch list

  • Jan 2, 2017: Code simplification: got rid of opt_resource at minimal cost
  • Jan 2, 2017: Added warning to Server::resource
  • Jan 3, 2017: Removed unnecessary public

[AmplabJenkins]

Can one of the admins verify this patch?

[dcrankshaw]

jenkins ok to test

[dcrankshaw]

This looks great. Thanks for contributing! I'll merge once the tests pass.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1120/
Test FAILed.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1122/
Test FAILed.

[dcrankshaw]

@withsmilo The formatter can be a little finicky. I just formatted and pushed to this branch, so it should clear the format checker now.

[withsmilo]

@dcrankshaw
Thank you. The formatter seems to have varying behavior across versions or systems.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1123/
Test FAILed.

[withsmilo]

I will check run_unittests.sh.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Clipper-PRB/1124/
Test PASSed.