Removed Zellner prior for damped coefficients. Updated prior for seas…

[devindg]

…onal variances

• The dynamic Zellner prior for damped coefficients has been removed due to instability. The default prior for damped coefficients is now N(1, 1).
• Default scale parameters for seasonal variances have been changed from (0.01 std(response))^2 to 10 (0.01 * std(response))^2.
• README.md updated to reflect changes
• Update to documentation to reflect changes
• New examples images uploaded to reflect changes