Restore hex to getrawtransaction vout scriptPubkey.

Commit be066fad accidentally removed the hex field.
This gets in the way of doing offline signing.

(credit belongs to sipa for actually looking for the
 cause instead of being lazy like me and just shrugging
 and writing the scriptpubkey from the asm.)
Merge pull request #3365 from gmaxwell/hexify

Restore hex to getrawtransaction vout scriptPubkey.