Implement password based session login

* Adjust URL's
  - rename /ipa/login -> /ipa/session/login_kerberos
  - add /ipa/session/login_password

* Adjust Kerberos protection on URL's in ipa.conf

* Bump VERSION in httpd ipa.conf to pick up session changes.

* Adjust login URL in ipa.js

* Add InvalidSessionPassword to errors.py

* Rename krblogin class to login_kerberos for consistency with
  new login_password class

* Implement login_password.kinit() method which invokes
  /usr/bin/kinit as a subprocess

* Add login_password class for WSGI dispatch, accepts POST
  application/x-www-form-urlencoded user & password
  parameters. We form the Kerberos principal from the server's
  realm.

* Add function  krb5_unparse_ccache()

* Refactor code to share common code

* Clean up use of ccache names, be consistent

* Replace read_krbccache_file(), store_krbccache_file(), delete_krbccache_file()
  with load_ccache_data(), bind_ipa_ccache(), release_ipa_ccache().
  bind_ipa_ccache() now sets environment KRB5CCNAME variable.
  release_ipa_ccache() now clears environment KRB5CCNAME variable.

* ccache names should now support any ccache storage scheme,
  not just FILE based ccaches

* Add utilies to return HTTP status from wsgi handlers,
  use constants for HTTP status code for consistency.
  Use utilies for returning from wsgi handlers rather than
  duplicated code.

* Add KerberosSession.finalize_kerberos_acquisition() method
  so different login handlers can share common code.

* add Requires: krb5-workstation to server (server now calls kinit)

* Fix test_rpcserver.py to use new dispatch inside route() method

https://fedorahosted.org/freeipa/ticket/2095

ipalib/krb_utils.py

@@ -42,7 +42,7 @@ ccache_name_re = re.compile(r'^((\w+):)?(.+)')
 
 #-------------------------------------------------------------------------------
 
-def krb5_parse_ccache(name):
+def krb5_parse_ccache(ccache_name):
     '''
     Given a Kerberos ccache name parse it into it's scheme and
     location components. Currently valid values for the scheme
@@ -55,12 +55,12 @@ def krb5_parse_ccache(name):
     does not exist it defaults to FILE.
 
     :parameters:
-      name
+      ccache_name
         The name of the Kerberos ccache.
     :returns:
       A two-tuple of (scheme, ccache)
     '''
-    match = ccache_name_re.search(name)
+    match = ccache_name_re.search(ccache_name)
     if match:
         scheme = match.group(2)
         location = match.group(3)
@@ -71,7 +71,10 @@ def krb5_parse_ccache(name):
 
         return scheme, location
     else:
-        raise ValueError('Invalid ccache name = "%s"' % name)
+        raise ValueError('Invalid ccache name = "%s"' % ccache_name)
+
+def krb5_unparse_ccache(scheme, name):
+    return '%s:%s' % (scheme.upper(), name)
 
 def krb5_format_principal_name(user, realm):
     '''
@@ -388,5 +391,5 @@ class KRB5_CCache(object):
         except KeyError:
             pass
 
-        self.debug('"%s" ccache endtime=%s (%s)', self.ccache_str(), result, krb5_format_time(result))
+        self.debug('KRB5_CCache %s endtime=%s (%s)', self.ccache_str(), result, krb5_format_time(result))
         return result