Add support for Scrum for Trello Points export

[collisdigital]

Added exporting of points values from card titles that are in brackets e.g. (0.5); this will also remove the points from the title and trim it to remove whitespace.

[collisdigital]

@trapias I think this is ready now; it should work fine with both Trello Plus and Scrum for Trello. I've tried to introduce some re-use for extracting floats from the card titles and updated the regexes. Example card titles that should extract correctly:

Card 1 (13)
Card 2 (14/5)
Card 3 (13) [5]
[5] Card 4 (10)
Card 5 (66.54/10.9987)
(987.654) Card [12.345] 6

[trapias]

@collisdigital thanks for your pull request, merged and published. Also fixed a couple of bugs with 1.9.27, now available here and on the Chrome Web Store in some minutes