adding dev warning when variable in mustache template is not found. Closes #720
adding dev warning if mustache helper isn't found. Closes #726
making test names smell the same
updating dev messages so that they look the same
adding dev logs for mustache_core as well
forgot to wrap dev tests in a check for can.dev
Merge pull request #927 from ekryski/mustache-dev-logging

Mustache dev logging