[rosalind] handle default and cli input in revc example
[rosalind] handle default and cli input in revc example

stmuk/perl6-examples,shlomif/perl6-examples,Quinny/perl6-examples,stmuk/perl6-examples,shlomif/perl6-examples,Quinny/perl6-examples,Quinny/perl6-examples,shlomif/perl6-examples,shlomif/perl6-examples,perl6/perl6-examples,perl6/perl6-examples,shlomif/perl6-examples,perl6/perl6-examples,Quinny/perl6-examples,stmuk/perl6-examples,perl6/perl6-examples,stmuk/perl6-examples,Quinny/perl6-examples,stmuk/perl6-examples,perl6/perl6-examples