122 comments in report

Fix for cellcounter/cellcounter#122. Lineage comments were already included in the report at [Line #45 of report.html](https://github.com/cellcounter/cellcounter/blob/master/cellcounter/main/templates/main/report.html#L45). 

This pull request supports:

* The inclusion of Overall Comments in the report
* Tidies up the naming of the cellcount instance context object to cellcountinstance in the view count view