Provide splits endpoint

**Is your feature request related to a problem? Please describe.**
Splits data is currently not provided. While it is good to have access to the raw unadjusted data as it's currently available, this data is useless without an endpoint which provides the splits data.

**Describe the solution you'd like**
Provide a new endpoint which lists all splits for a ticker.

**Describe alternatives you've considered**
This is different from issues #131 and #175 which request an endpoint that provides adjusted data.

**Additional context**
Once this new endpoint is available, I can then use the splits to convert unadjusted data to adjusted data on my own. Without this endpoint, I will have to reload all historical data daily which will place a substantial burden on your server.