Add Support for LinkBlock notion types

This release includes support for a new block type in Notion: link blocks. They can be created as follows:

@client = NotionAPI::Client.new(ENV["token_v2"])
@page = @client.get_page("https://www.notion.so/danmurphy/Testing-227581d35fc94fa1a5f9fda1e8478d1e")
@page.create(NotionAPI::LinkBlock, "ea93213d1f21439c870fbe91503e76fe")

v1.1.3

Polymorphic-based redesign of the API internals. Additionally, better support for creating image blocks via public URLs.

v1.1.2

Better support for Collection View property names- non-alphanumeric characters are removed.

v1.1.1

This version provides better support for working with root collection view pages. Now, you can pass a collection view page URL and retrieve the page, access the rows, a specific row, and read and write to specific cells. Additionally, you can now work with any BASIC property type! This includes select, multi-select, date, people, and other properties.

v1.1.0

All property types are fully functional for Collection Views, and add_row now works on root pages.

v1.0.6

Updates to .add_row to make it more user-friendly

v1.0.5

See #16 for a more detailed overview of the updates pushing in this new release.

Overall, you can now read and write data to specific properties in specific rows due to some dynamically-created methods that are built each time you retrieve a CollectionView's rows.

v1.0.4

Enhancements

Added the CollectionViewPage, which allows users to retrieve a full-page Collection View.

v1.0.3

Updates to active_user_header so that, when a user passes the active_user_header parameter to the NotionAPI::Client, that information successfully gets passed to parent classes.

Major improvements!

1. Now, when the .duplicate method is called, both the title of the block and its properties are duplicated. This means a todo block that is checked will remain checked, and a text block with a red background and purple font will be duplicated with the same styling.
2. When a Callout and Page block are created, they are randomly assigned an emoji. This is a minor improvement for styling purposes... but it looks a lot better and was something I wanted to push through.
3. The block types are now re-factored into a sub-folder and they each have their own respective file. That'll make it easier to add more methods for specific blocks in the future.