added missing handler for interpreter arguments

when text is POSTed as an executable job (using X-Zerovm-Execute header)
the shebang line can contain not only path to interpreter but also interpreter command line args
this change adds handling for these args, now the args are properly inserted into nvram file

brief digression:
format of shebang line is not standardized in POSIX or any other *NIX documentation
most systems "safely" assume that shebang does not contain anything but path to the interpreter
but in Linux and some other modern systems shebang can contain command line arguments
this is why it's handled here
Merge pull request #25 from pkit/proxy_fixes

added missing handler for interpreter arguments