switch rest demo to https in the default config

added is(Not)Null and Undefined methods to empty.util …

This merge closes #134

Rename the HAL link

Fix pagination issues

...angular 4 update

closes #128 

fixed an issue where if there is only one bitstream it would be returned as a single object and not an array in the item.bitstreams property

Angular upgrade: this connects to #83 and this connects to #86