Squashed 'third_party/poco_1.5.3/' content from commit cd607b6

git-subtree-dir: third_party/poco_1.5.3
git-subtree-split: cd607b6f28908526677246dbcc5f76cf1d6617e6
Merge commit '86d034c52ad01740d2e58c51b688d7f2ffb76168' as 'third_party/poco_1.5.3'
add options to only build parts of poco, change some other options do different defaults
changed cmake files to use standard poco libraries
added cmake project path so POCO works as a subproject, added XML_STATIC flag so PocoXML works when static linking on Windows
added winsock link libs so http stream links on Windows, updated docs
removed old hacked up poco, cleaned up setup.py, ran OSX tests