[WG: I18N & L10N] change in strings for lesson builder

[Charles Hedrick]

I have just made several minor changes in strings for lesson builder. The changes are shown in revisions 100766 and 100767, for 1.4 and 1.3, respectively.

See https://jira.sakaiproject.org/browse/LSNBLDR-34

That Jira lists a number of minor issues I'll be working on for a few weeks. I think I've made all the string changes that will be needed for them at the same time, in an attempt to simplify your lives.