Remove existing dependencies and add bootstrapbase as mandatory

[Info 3bits]

Actually the block_course_overview is required as a dependency of the theme but bootstrapbase is not include when it is mandatory or the theme will break.

[Jeremy Hopkins]

In case you are not aware the block is required for the "this course" dropdown list.

[Info 3bits]

Ok, added again

[Jeremy Hopkins]

That block is core anyway so should never cause a problem unless someone had un-installed it.

[Info 3bits]

Fix #258

→ <<cset ad69672a96b1>>

[Info 3bits]

Fix #258

→ <<cset c5a35b4545db>>