add notext option, fix paste without text handling

Now text is taken if no `--notext (-q)` argument is passed.

If that flag used, paste will be created with empty text,
but file for send must be specified

If `notext` arg is not used, text will be taken in next order:
* from `--text (-t)` argument
* from stdin (forcibly)

Here's no ability create paste without any text.

pbincli/cli.py

@@ -34,6 +34,7 @@ def main():
     send_parser.add_argument("-F", "--format", default="plaintext", action="store",
         choices=["plaintext", "syntaxhighlighting", "markdown"], help="format of text (default: plaintext)")
     send_parser.add_argument("-t", "--text", help="comment in quotes. Ignored if used stdin")
+    send_parser.add_argument("-q", "--notext", default=False, action="store_true", help="don't send text in paste")
     send_parser.add_argument("-p", "--password", help="password for encrypting paste")
     send_parser.add_argument("-d", "--debug", default=False, action="store_true", help="enable debug")
     send_parser.add_argument("--dry", default=False, action="store_true", help="invoke dry run")