CourseAPI: Get class method for retrieving class details.

[azharichenko]

As a suggestion made by @JohnLinahan, get_class_description will become get_class with more details which include time, classrooms, days, section, etc.

New Package Changes

• Updated README.md to reflected the changes made to CourseAPI

New CourseAPI Changes

• get_class_description has become get_class with new functionality.
• There are now two private functions for data extraction.
  • _extract_description(text) which grabs the description of the course from the web page
  • _extract_details(text) which grabs the line of details about the certain class
  • This includes time, classroom, days, and section
• Updated documentation and added new example

[azharichenko]

@RitwikGupta Ready to pull.