Install pylint explicitly in custom linter action

Change-Id: I61891ef6682af209ee94b187b247f5b779e83c8a

Update CHANGELOG for v2.5.0

Change-Id: I20717c787024f7fbace2f7735f4950529d3a17e7

Update CHANGELOG for v2.4.3

Change-Id: Ia6d004558fd1cac6f394bfb7568c7bb9124aa9cc

Update CHANGLOG for v2.4.2

Change-Id: I61ec5e9c463448b840409c6ca2b0fe6d9f35a508

Fix appveyor builds

Also updated .travis.yml to be consistent and corrected v2.4 link
in CHANGELOG.

Change-Id: I993a296b546c537f67abeb6bc4f9c03799ffa7dc

Include pssh-box.py in release

Also updated API keys for both Travis and Appveyor as the previous ones
have expired. And removed shared_library release to avoid confusions.

Fixes shaka-project#550.

Change-Id: I81b1531a9abb9669be54a2e302346e194d7c363e

Update the CHANGELOG for v2.3.0

Change-Id: I8cf0591672d580a4bb3245170f1f34b0b7149946

Update CHANGELOG for v2.2.1

Change-Id: Iedd53d423b5c71ab8aba8b671ca8fa4ad3ab933b