Author: Jun Pataleta
MDL-65937 mod_lesson: Replace concatenated strings with lang strings
http://git.moodle.org/gw?p=moodle.git;a=commit;h=32c7889212c1dff7b1f8912b9012da9dc2d05610
http://github.com/moodle/moodle/commit/32c7889212c1dff7b1f8912b9012da9dc2d05610
+ 3.8 en [attemptinfonograde,mod_lesson]
+ 3.8 en [attemptinfowithgrade,mod_lesson]
+ 3.8 en [notcompletedwithdate,mod_lesson]