Change minimum treshold and tests for % explained
Fix formatting to use two decimal places

Changing the minimum threshold for an axis to be considered, required us
to change the formatting of the string to have two decimal places,
otherwise it would show 0 for values < to 1.

Fixes #226
Fix error as pointed out by @antgonza
Merge pull request #240 from ElDeveloper/issue-226

Fixes issue 226 - minimum percent explained
Fixes key tab not using the available space

The key tab was not previously using all of the available space on
screen, I've made some changes to the CSS sheet to make this the case
and added some padding when the table is formatted.

Fixes #158
Add note to changelog about the key tab
Merge pull request #243 from ElDeveloper/issue-158

Fixes key tab not using the available space