Go run shell commands

[at15]

For #7 we have the following requirements

• user write their test script as string, ie: go test .
• show the output and get exit status

Current problems are

• os/exec require name, arg1, arg2, .... while user input is string
• os/exec seems can not handle situation like go test -v -cover $(glide novendor)
• use sh -c "command here" via os/exec seems not working
• have a minimal sample and ask question on so

Some CI written in golang could an example

• https://github.com/jakecoffman/gorunner/blob/master/service/runs.go
• https://github.com/drone/drone
• $(glide novendor) is subshell as mentioned in this answer for question
• https://github.com/codeskyblue/go-sh like python-sh, for easy call shell with golang.

[at15]

split the string like shell does is the main problem. cc @gaocegege