v.2.2.8 build 2018082000 for moodle 3.5

Changelog

The format is based on Keep a Changelog.

[2.2.8] - 2018-08-20

Changed

• Change all behat test, now using chorme last version, removing firefox v.47 (very old version)
• Update to reCaptcha2 (#197)
• Fix activity order in {USERRESULTS} tag is not the same as in course (#169)
• Fix date received column in verify page (#171)
• Fix download all of the users certificate data in issue certificate page (#182)
• Fix {DATE} variable (#193)
• Fix rrror while creating Simple Certificate activity in moodle 3.5.1 (#206)

Removed

• FPDI and UUID from plugin's lib folder (#183)