Tag for release version 0.8.3

drop php 5.3 from travis config

Merge branch 'develop' in preparation for 0.8.1

(missed a pull request)

Merge branch 'develop'

Address file system path compatibility issues

Closes dompdf#1191

Use strict equality when testing for 0

Restrict access to sensitive www content to authenticated users

Protocol relative url support for build url helper

Closes dompdf#1026

tweak instructions for non-composer installations

Tagging release 0.6.1