retaining substring within single quotes as a integral part when parsing arg string

// "arg1 arg2 'hello world' arg4" --> ["arg1", "arg2", "'hello world'", "arg4"]

// addressing Shinjae's needs as follows:

Hi Wei,

I got error due to space characters:

worker: start cmd=gwas_prepare_variation_for_gwas, args=[http://kbase.us/services/ws kbasetest:gwtest http://kbase.us/services/shock-api atpopvar1 atpopvar1.filtered 0.05 'test test']
!!!RunWorkunit() returned error: wait_cmd=gwas_prepare_variation_for_gwas, err=exit status 1

However, if I execute the same command on the terminal, then no problems… 

gwas_prepare_variation_for_gwas http://kbase.us/services/ws kbasetest:gwtest http://kbase.us/services/shock-api atpopvar1 atpopvar1.filtered 0.05 'test test'