Invert skip_verify to be opposite of "verfy" flag in pillar

- skip_verify: {{ true if package.verify else false }}
will be true when package:verify is set to true
And that confuses.

"skip verify" means "skip any verify process" and package should
not be verified during installation

Currently, for disabling verification we use:
linux:
  system:
    package:
      netapp-offload-tool:
        verify: true

And anyone who is reading reclass model can be easily perplexed.
Patchset fixes that issue.

Change-Id: I38d60ff3dbe651e14898c4937fc7dddad36204be

linux/system/package.sls

@@ -33,7 +33,7 @@ linux_extra_package_{{ name }}:
   - hold: {{ package.hold }}
     {%- endif %}
     {%- if package.verify is defined %}
-  - skip_verify: {{ true if package.verify else false }}
+  - skip_verify: {{ "False" if package.verify else "True" }}
     {%- endif %}
   {%- else %}
     {%- if package.version is not defined %}