Updating CHANGELOG for release v0.3.0

[kmadisa]

This PR serves to capture some of the major changes that were made to the library since the last release.

Screenshots or code snippets (if appropriate):

• N/A

Definition of Done Checklist

• [x] Code meets our python style guidelines?
• [x] Unit tested (coded, passed, included)?
• [x] Requested at least 2 reviewers?
• [x] Commented code, particularly in hard-to-understand areas?
• [x] Made corresponding changes to the documentation (e.g. Python documentation, System Engineering Documentation, version description updates, README file, etc)?

JIRA: N/A