Make lint work on Fedora 22.

pylint added 'confidence' parameter to 'add_message' method of PyLinter.
To be compatible with both, pre- and post- 1.4  IPALinter must accept
the parameter but not pass it over.
Also python3 checker was added and enabled by default. FreeIPA is still
not ready for python3.
Additionally few false-positives was marked.

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipapython/dnssec/ldapkeydb.py

@@ -23,6 +23,7 @@ def uri_escape(val):
     assert len(val) > 0, "zero-length URI component detected"
     hexval = hexlify(val)
     out = '%'
+    # pylint: disable=E1127
     out += '%'.join(hexval[i:i+2] for i in range(0, len(hexval), 2))
     return out