Added django 1.7 and 1.8 to travis file
Added django 1.7 and 1.8 to travis file

Added excludes for incompatible combinations

xavierdutreilh/django-mailviews,joshowen/django-mailviews,disqus/django-mailviews,joshowen/django-mailviews,xavierdutreilh/django-mailviews,danxshap/django-mailviews,disqus/django-mailviews,danxshap/django-mailviews