Remove multiple functions with `faas-cli remove` by name

It is not entirely clear whether multiple functions can be removed with a single faas-cli remove invocation. Suppose I have the following functions:

$ faas-cli version
  ___                   _____           ____
 / _ \ _ __   ___ _ __ |  ___|_ _  __ _/ ___|
| | | | '_ \ / _ \ '_ \| |_ / _` |/ _` \___ \
| |_| | |_) |  __/ | | |  _| (_| | (_| |___) |
 \___/| .__/ \___|_| |_|_|  \__,_|\__,_|____/
      |_|

CLI:
 commit:  619282afd0dd2520a7669ec9396282ce2348a35f
 version: 0.17.7

Gateway
 uri:     http://[...]
 version: 0.27.12
 sha:     4e20249bc0703954244d4be98eaa6c2bcb68cb83


Provider
 name:          faas-netes-ce
 orchestration: kubernetes
 version:       0.18.16 
 sha:           cac64e04f91db67b75d055d3ee4d286b303575db
Your faas-cli version (0.17.7) may be out of date. Version: 0.17.8 is now available on GitHub.
$ faas-cli list
Function                        Invocations     Replicas
figlet                          103819          1    
ocr                             8               1    
shasum                          825             1 

Then I run the following command:

$ faas-cli remove figlet shasum ocr
Deleting: figlet.
Removing old function.

After some seconds, this is the result:

$ faas-cli list
Function                        Invocations     Replicas
ocr                             8               1    
shasum                          825             1  

When I run faas-cli remove --help, the help message says that it is possible to remove multiple functions, but only if they are specified via a YAML config. If I specify functions by name, I can remove only one function at a time. I think it would be both easy and useful to add support for removing multiple functions in the latter mode.

Start with the faas-cli remove command and its --help output, comparing named arguments with YAML-config behavior. Trace how multiple names are handled, then verify that faas-cli remove figlet shasum ocr removes all three while existing single-name and YAML modes remain unchanged.