Fixed double-freed of requests map, and memory leak of message2key

Change-Id: I602fe93f88b8399156f3e9eb7f38486e6752e4b7

Conflicts:
	lib/index.js
Timeouts are configurables

Change-Id: Ic8020486415325f8f8ac21d8ad01b96e52fdfd68

Conflicts:
	lib/index.js