changed getFilter function to descern between '3_d' and '3_m'

[fluentinstroll]

addresses issue #215

changed from

if (tester.startsWith('3'))
        tester = '3_days';

to

if (tester.startsWith('3_d'))
        tester = '3_days';
    else if (tester.startsWith('3_m'))
        tester = '3_months';

in order to properly discern between months and days as mentioned above.

[fluentinstroll]

I believe this failed because the tests expect the input of "3" to spit out "3_days" which will not happen with my changes - I didn't want to change the tests because they weren't within the purview of the issue I was addressing. However, I can change them with permission.

[tehhowch]

You should update the tests as well 👍

[tehhowch]

Lgtm