Meta expressions are not evaluated

[Stan Lagun]

Only a constant values can be provided as a values for Meta properties.
So it is possible to say:

Meta:
  m:Type:
     val: 4

but not

Meta:
  m:Type:
     val: 2 + 2

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/291152

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/291152
Committed: https://git.openstack.org/cgit/openstack/murano/commit/?id=188315377b2718bf5f4057ef86811ec7b0af8cd4
Submitter: Jenkins
Branch: master

commit 188315377b2718bf5f4057ef86811ec7b0af8cd4
Author: Stan Lagun <email address hidden>
Date: Thu Mar 10 15:52:06 2016 +0300

    Meta values evaluation was fixed

    Meta property values were not evaluated.
    As a result property value 4 considered to be an integer
    but 2+2 to be a string "2+2". This commit fixes 2 things:

    1) Adds evaluation to property values making embedded
        YAQL expressions to be evaluated
    2) Changes the contexts on which Meta is calculated. Before
        This fix everything was done in caller context thus value
        of the local variables of functions where Meta was accessed
        could be used in Meta definitions

    Change-Id: I50de9199e5efa36a668fd3640a016a723326cae7
    Closes-Bug: #1555617