* Adds kn revision delete command
* Adds unit tests for revision delete command
* Adds integration tests for revision delete command
Added revision delete command tests in new workflow namely
TestRevisionWorkflow.
* Removes extra line and renames an import alias
* Adds 10 seconds sleep between service create and revision delete
Also adds check for 'No resources found' while grabbing revision name.
* Clean up imports
* Removes the pause after service create
* Updates testing output strings in unit and e2e
* Updates post goimports on hack and test dirs
Creates four subpackages for now:
1. kn/commands - inludes types.go for common
struct and other common files and misc commands
2. kn/commands/service - all 'kn service *' commands
3. kn/commands/revision - all 'kn revision *' commands
4. kn/core - contains the root.go and other top level
for code and testing
5. refactors:
a. split .../commons/human_readable_flags.go into three
b. modifies the HumanReadableFlags.ToPrinter to get pass
a function that sets the columns and fields
Had to refactor all tests to avoid cycles.