Fix ignored headers + unnecessary major version check

[AT0myks]

I was wondering why Outlook emails didn't have any flags. Turns out data[1] seems to contain the end of data[0][0]. For the 3 other servers I have tested, data[1] is just a single closing parenthesis but in the case of Outlook it contains the flags.
Here's the an example of the output of

print(data[0][0])
print(data[1])

for Gmail:

b'1 (UID 9854 FLAGS (\\Seen) BODY[] {25498}'
b')'

and here it is for Outlook:

b'1 (BODY[] {5984}'
b' FLAGS (\\Seen) UID 354)'

so the fix is to simply concatenate them.
I hope this doesn't break things for other servers, if it does we can just add a check for the length of data.

Also fixed a version check that's not necessary since Imbox is for 3.3+.