cubicweb-brainomics #3348088 Make the startup page load with bootstrap 3.0 [validation pending]

Currently, the startup page is not accessible when using bootstrap 3.0.

priorityimportant
typebug
done in0.7.0
load0.500
load left0.000
closed by#2a63796abb42 [views] Backport main_header monkeypatch from squareui (closes #3348088)
patch[views] Backport main_header monkeypatch from squareui (closes #3348088) [applied]