Added linting check to a pre-commit hook

refs 648530009d

- Naz has broken the main too many times - it's time to stop the atrocities.
- Having a lint check as a pre-commit hook will make it really hard commiting code with linting errors

.github/hooks/pre-commit

@@ -1,4 +1,15 @@
 #!/bin/bash
+yarn lint
+lintStatus=$?
+
+if [ $lintStatus -eq 0 ]
+then
+  echo "linting succeeded"
+else
+  echo "linting failed"
+  exit 1
+fi
+
 # Modified from https://github.com/chaitanyagupta/gitutils
 
 green='\033[0;32m'