Issue #217: Indent html in our html output
* add a dependency in composer.json to "gajus/dindent"
* remove manual indent and line breaks in Utils::printSimpleTable() used in the accesskey view as an example
* fixed a not closed <div> in the process
Merge pull request #218 from mozfr/issue-217-indent-generated-html

Issue #217: Indent html in our html output