Comparison of MANTA_KEY_ID fingerprint to agent fingerprint is broken for MD5

[rjloura]

Fixes #51

[rjloura]

Ran tests with

MANTA_KEY_ID=SHA256:<sha256 key>
MANTA_KEY_ID=MD5:<md5 key>
MANTA_KEY_ID=<md5 key>
MANTA_KEY_ID=~/.ssh/id_rsa

Outputs were all the same:

$ ./test/test.py
mantaclient/cleantestarea/clean ... ok
mantaclient/dir/listheaddel ... ok
mantaclient/dir/put ... ok
mantaclient/link/put ... ok
mantaclient/manyfiles/count [slow] ... ok
mantaclient/misc/imports ... ok
mantaclient/misc/version ... ok
mantaclient/object/putgetdel ... ok
mantash/find/empty ... ok
mantash/find/type ... ok
mantash/ls/bare ... ok
mantash/ls/dir ... ok
mantash/ls/dirstar ... ok
mantash/options/help ... ok
mantash/options/version ... ok