Need more helpful error message in cases when IMAGE|DIRECTORY or appname is missing.

[sangee2004]

Server version - acorn version v0.6.0-132-gdc73d55a+dc73d55a

Steps to reproduce the problem:

 acorn run --update  
  ✗  ERROR:  resource name may not be empty

% acorn run --replace 
  ✗  ERROR:  resource name may not be empty
sangeethahariharan@Sangeethas-MBP example1 % 

acorn run works like acorn run . but that is not the case with acorn run --update and acorn run --replace. Why?

In the above cases , a more helpful error message to indicate that user needs to provide IMAGE|DIRECTORY if wanting to create a new app or "-n= if they want to update existing apps.

[jsilverio22]

@sangee2004 this was resolved somewhat by #1445 in that now acorn run --update defaults to behavior of acorn run so err message should no longer be displayed. moving to QA to confirm this

[sangee2004]

Tested with acorn version v0.6.0-136-gc2c4989d+c2c4989d

acorn run --update and acorn run --replace results in new app being created.