Modify ipalib.rpc to support JSON-RPC in addition to XML-RPC.
This is done by subclassing and extending xmlrpclib, because
our existing code relies on xmlrpclib internals.

The URI to use is given in the new jsonrpc_uri env variable. When
it is not given, it is generated from xmlrpc_uri by replacing
/xml with /json.

The rpc_json_uri env variable existed before, but was unused,
undocumented and not set the install scripts.
This patch removes it in favor of jsonrpc_uri (for consistency
with xmlrpc_uri).

Add the rpc_protocol env variable to control the protocol
IPA uses. rpc_protocol defaults to 'jsonrpc', but may be changed
to 'xmlrpc'.
Make backend.Executioner and tests use the backend specified by
rpc_protocol.

For compatibility with unwrap_xml, decoding JSON now gives tuples
instead of lists.

Design: http://freeipa.org/page/V3/JSON-RPC
Ticket: https://fedorahosted.org/freeipa/ticket/3299

This change makes single_value consistent with the raw property.

https://fedorahosted.org/freeipa/ticket/3521

This is achieved by storing both decoded and encoded attribute values in
LDAPEntry and synchronizing changes between them whenever an attribute is
accessed.

Added a new property "raw" to LDAPEntry. It provides a dictionary-like
object which can be used to directly access encoded attribute values.

https://fedorahosted.org/freeipa/ticket/3521

Nose doesn't pick up directories that don't begin with 'test'.
Rename ipatests/test_ipaserver/install to test_install so that it's run.

Also, merge test_ipautil.py from ipapython/test into tests/test_ipapython,
so the whole test suite is in one place.

Rename the 'tests' directory to 'ipa-tests', and create an ipa-tests RPM
containing the test suite

Part of the work for: https://fedorahosted.org/freeipa/ticket/3654