Prepend 0x to gpg hex keyids to support gnupg in version 2.

- e.g. 12345678 is queried as 0x12345678
Refactoring plugins: made demos.py stand alone
Fix event search bug
Merge pull request #538 from codeburg/fix_keyid_on_gnupg_v2

Prepend 0x to gpg hex keyids to support gnupg version 2.
Read me, Seymore
Plugin refactoring progress (issue #547)