Explorer interface was cluttered by too many horizontal dividing sections in the header. 'Explorer' title has been dropped in favour of making the current section index page feel more like the title. breadcrumb also toned down
Some icon font use converted to REM due to IE9's incompetent understanding of pseudo-elements
Handle SQLite substr syntax

Addresses https://github.com/torchbox/wagtail/issues/11
Merge branch 'master' of github.com:torchbox/wagtail
Merge remote-tracking branch 'upstream/master'