v0.7.0

Features:

• Rename http::Context::FindClientIP to http::Context::FindClientIPFromURI
• Add http::Context::FindQueryFromURI and http::Context::GetQuery. Thanks @sumory @sotex
• Improve the performance of gettimeofday on windows. Thanks @yuangu

Fix bugs:

• Fix EventLoop::watcher_ notify failed after a fork() #56