Refactor cherami-admin and cherami-cli code

[kobeyang]

Basic idea:

1. Create folder common under cmd/tools, and create lib.go in it to store the common flags and commands used by both cli and admin.
2. Delete tools/cli/lib.go and move the corresponding functions to tools/common/lib.go. Add a parameter serviceName to these common functions to differentiate cli and admin.
3. Cherami-cli will just use the common functions and Cherami-admin will use some admin-specific functions in tools/admin/lib.go.

Not sure whether this is the best way to do this, please leave any suggestion whichever you want.

[CLAassistant]

All committers have signed the CLA.

[coveralls]

Coverage decreased (-0.02%) to 68.292% when pulling a8246dd on refactor into 51b6724 on master.

[kirg]

@kobeyang i just committed PR #246 that will probably cause some merge conflicts for you .. (sorry about that .. :-))

[kobeyang]

Merge with Kiran's change in PR#246.

[thuningxu]

Please move the menu in cmd/tools/admin/main.go to the library.

[thuningxu]

Reviewed in person. Generally looks good. Please remove the *Helper functions.