readd signing code
add -s / --sign flag
cleanup signing.c, newlines shouldn't be in errx output
better error handling
rudamentory support for signing
use openat for gpgme_sign
cleanup gpgme_verify to use openat
fix signature fd code
refactor signature checking and handling
fix trace message
Merge branch 'signing'

* signing:
  fix trace message
  refactor signature checking and handling
  fix signature fd code
  cleanup gpgme_verify to use openat
  use openat for gpgme_sign
  rudamentory support for signing
  better error handling
  cleanup signing.c, newlines shouldn't be in errx output
  add -s / --sign flag
  readd signing code

Closes #22.