Adding status checks for languages and their versions

[pgayee694]

Currently, if the required languages/interpreters/compilers aren't installed, the executor will throw an error. Instead it would be better to have a status to each version to see if the language is installed and let execution continue if the language is not installed. One method might be to create and catch exceptions, and another is to use shutil.which (docs: https://docs.python.org/dev/library/shutil.html#shutil.which).