Merge pull request pubnub#114 from pubnub/develop

Release 4.18.0

Merge branch 'develop'

Merge branch 'develop'

Merge branch 'develop'

Develop (pubnub#103)

* swap uuid generator with support for IE9 and IE10

* add delete_messages (pubnub#102)

* 4.16.0

lib changes

fix up changelog

update changelog