code improvements

[pasupulaphani]

• Using the prototype constructor pattern for the lib/redis_cache.js module. Would be more memory efficient than declaring a new object for each instantiation

• If you are targeting ES6 then I believe you are safe using the native bind rather than lib/util/bind.js

[coveralls]

Coverage increased (+1.1%) to 78.519% when pulling e658a53 on pearlshare:master into 6f15c88 on pasupulaphani:master.

[coveralls]

Coverage increased (+1.5%) to 78.832% when pulling df8e41f on pearlshare:master into 6f15c88 on pasupulaphani:master.