adding new attributeContains assertion and tests

Added a new attributeContains assertion and the corresponding test files. This allows matching on bits of attribute values

Status: **Opened for visibility**
Reviewers: @kbingman @scalvert 

## Changes
- added new attributeContains.js file
- added new testAttributeContains.js test file

## How to test drive this PR
- switch to this branch
- add a new nightwatch test
- use attributeContains command
- verify it works