Import and modified the project coxpcall for error handling; Create TODO.md.

Signed-off-by: Xiongfei(Alex) Guo <xfguo@credosemi.com>
Fix minor issuses; Move all util functions to util.lua.

Signed-off-by: Xiongfei(Alex) Guo <xfguo@credosemi.com>
Minor bug fixed.

Signed-off-by: Xiongfei(Alex) Guo <xfguo@credosemi.com>
Add an error handling test for echo server.

Signed-off-by: Xiongfei(Alex) Guo <xfguo@credosemi.com>
Merge pull request #2 from xfguo/error-handling

Error handling for actors.