Fix a few typos.

Author: rfoliva

CONTRIBUTING.md

@@ -9,12 +9,12 @@ Please note we have a code of conduct, please follow it in all your interactions
 
 1. Ensure any install or build dependencies are removed before the end of the layer when doing a 
    build.
-2. This project uses flake8 to conform with common Python standards. Makse sure
+2. This project uses flake8 to conform with common Python standards. Make sure
    to run your code through linter using latest version of flake8, before pull request.
 3. Bad documnentation is a Bug. If your change demands documentation update, please do so. If you
    find an issue with documentation, take the time to improve or fix it.
-4. pytest is used for automated testing. Please make sure to update tests are needed, and to run
-   `make test`, before submitting your pull request. This should prevent issues with TravisCI and
+4. pytest is used for automated testing. Please make sure to update tests that are needed, and to run
+   `make test` before submitting your pull request. This should prevent issues with TravisCI and
    make the review and merging process easier and faster.
 5. Update the README.md with details of changes to the interface, this includes new environment 
    variables, exposed ports, useful file locations and container parameters.