heat validation improvements and error verbosity

[Steve Lipinski]

When validating a template, very terse errors are usually provided.

Specifically, the case I encountered - where a parameter was defined yet the type attribute was accidentally omitted, e.g.,
  internal_network_type:
    label: Internal Network Type
    description: The type of internal network to be used

The error in the engine-api.log:
2014-03-18 13:47:08.303 46002 ERROR root [-] Unexpected error occurred serving API: u'\'Type\'\nTraceback (most recent call last):\n\n File "/usr/lib/python2.6/site-packages/heat/openstack/common/rpc/amqp.py", line 461, in _process_data\n **args)\n\n File "/usr/lib/python2.6/site-packages/heat/openstack/common/rpc/dispatcher.py", line 172, in dispatch\n result = getattr(proxyobj, method)(ctxt, **kwargs)\n\n File "/usr/lib/python2.6/site-packages/heat/engine/service.py", line 60, in wrapped\n return func(self, ctx, *args, **kwargs)\n\n File "/usr/lib/python2.6/site-packages/heat/engine/service.py", line 383, in validate_template\n tmpl_params = parser.Parameters(None, tmpl, validate_value=False)\n\n File "/usr/lib/python2.6/site-packages/heat/engine/parameters.py", line 360, in __init__\n self.params = dict((p.name, p) for p in parameters())\n\n File "/usr/lib/python2.6/site-packages/heat/engine/parameters.py", line 360, in <genexpr>\n self.params = dict((p.name, p) for p in parameters())\n\n File "/usr/lib/python2.6/site-packages/heat/engine/parameters.py", line 355, in parameters\n yield Parameter(name, schema, value, validate_value)\n\n File "/usr/lib/python2.6/site-packages/heat/engine/parameters.py", line 144, in __new__\n param_type = schema[TYPE]\n\nKeyError: \'Type\'\n'

The heat client output:
ERROR: Type

It would be nice if the validator would indicate the problematic parameter, e.g.,
ERROR parameter 'internal_network_type' missing required attribute 'type'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/86420

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/86420
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=4c582a2bc074009d2c7f5ae189c989c0b686cd04
Submitter: Jenkins
Branch: master

commit 4c582a2bc074009d2c7f5ae189c989c0b686cd04
Author: Jay Dobies <email address hidden>
Date: Wed Apr 9 14:55:24 2014 -0400

    More specific exceptions when validating params

    In addition to the example cited in the bug, this updates a few other
    exception messages to indicate the name of the parameter that is failing
    validation.

    Change-Id: I1b7729305988444dc15abd6e5d958f443efc091d
    Closes-Bug: #1294295