luci-base: Make uci mode strings match iwinfo mode strings

uci mesh was being displayed as 'Mesh', while iwinfo mesh was being
reported as 'Mesh Point'. Unify those. Update getActiveModeI18n to deal
with all the values iwinfo returns. Fix the incorrect 'Mash'
translation.

Signed-off-by: Evan Benn <evan.benn@morsemicro.com>