Add longer time periods to Dashboard filter

[ricanddorry]

As a bioacoustician looking for annual patterns in the OrcaHello tags,
I want to be able to filter the OrcaHello Dashboard results (i.e. the tag cloud) by these longer time periods:

• 3 months
• 6 months
• 1 year

In addition to keeping the existing options:

The default initial filtering of 1 month is great and fast, so can stay as is. These intermediate longer time periods I hope will load faster than All -- the only existing option >1month.