The COVIDcast export tool provides code snippets using the old API clients

[nmdefries]

When constructing a fetch query using the GUI data export tool on our main website, we auto-construct python and R code snippets at the bottom of the page. There are two problems with the code snippets generated:

• the code uses the old python and old R API clients, not the new ones (epidatr and epidatpy)
• weekly signals don't include the time_type = "week" param so will never work correctly