Fix policy manager loading

The policy manager was not loading due to it being invoked
with the wrong path.  This patch fixes that problem by
looking for the policy manager in node_modules.

Jira issue: WP-968
Stop attaching a random id to the message object

It's not in use anymore

Jira-issue: WP-978
Merge pull request #10 from aldafu/WP-978-remove-msgid

Stop attaching a random id to the message object
Make the policy manager mandatory.

Authorisation is a necessary part of webinos.  To not have it, is to
run without adequate security.  Having *a* policy-manager module should
therefore be mandatory, not optional.

Jira issue: WP-981
Merge pull request #8 from jplyle/fix-policy-integration

Fix policy manager loading
Merge pull request #11 from jplyle/make-policy-manger-mandatory

Make the policy manager mandatory.
Update package.json
Don't rely on information in serviceCache.json

Fixes "gatherLinks" message to only return available services.

Jira-issue: WP-1002
Merge pull request #12 from aldafu/WP-1002-build-serviceCache-from-available-mods

Don't rely on information in serviceCache.json
Fix service discovery not being found

As part of the others fixes for WP-848 this was missing. webinos.discovery
is now defined in the discovery wrt code itself.

Jira-issue: WP-848
Merge pull request #13 from aldafu/WP-848-fix-missing-discovery

Fix service discovery not being found