[Documentation:Developer] Removed travis docs (#566)

We no longer use Travis CI, so the documentation has been mostly updated
to no longer show our uses in Travis CI

Co-authored-by: Barb Cutler <[email protected]>

_docs/developer/software_and_system_design/coding_style_guide/python.md

@@ -17,4 +17,4 @@ pip3 install flake8 flake8-bugbear pylint
 and then you can just run `flake8` at the root to check all files or pass it an individual file to check just that.
 To see all files that are currently checked as part of Travis-CI, please look at the `.flake8` config file.
 
-For pylint, you can just run `pylint --recursive=y .` at the root to check all files or pass it an individual file.
+For pylint, you can just run `pylint --recursive=y .` at the root to check all files or pass it an individual file.

_docs/developer/testing/linting_static_analysis.md

@@ -26,9 +26,6 @@ python3 -m flake8
 python3 -m pylint --recursive=y .
 ```
 
-_NOTE: Our Travis CI testing currently [excludes a number of legacy source code files](https://github.com/Submitty/Submitty/blob/master/.flake8).
-from Python linting, though there is effort to bring more and more of them under flake8._
-
 Optionally, you can pass in a specific file or directory to only lint that file or directory, e.g.:
 
 ```bash