Fixed evaluation of empty policy set

Evaluation is set to INAPPLICABLE when policy set is empty

Jira-issue: WP-886
Added new jasmine tests

Addes jasmine tests related to:
- empty policy set
- empty policy
- empty file

Jira-issue: WP-886
Fixed jasmine tests

Jira-issue: WP-886
Change README.md to reflect correct build instructions

Updated the readme to mention npm install and test.

Jira issue: WP-949
Merge pull request #2 from ccameroni/WP-886-empty-policyset

WP-886 empty policyset