Made Command class __repr__ method more robust

[BrentWilkins]

I started some work based on one of imaplib's examples.

IMAP4 Example

import getpass, imaplib

M = imaplib.IMAP4()
M.login(getpass.getuser(), getpass.getpass())
M.select()
typ, data = M.search(None, 'ALL')  # ← This is more supported now
for num in data[0].split():
    typ, data = M.fetch(num, '(RFC822)')
    print('Message %s\n%s\n' % (num, data[0][1]))
M.close()
M.logout()

I noticed that passing None as the first parameter got me an exception. To improve the robustness of the code, I added a generator expression that converts any NoneTypes to empty strings.

[bamthomas]

thank you @BrentWilkins