Add board and advisory-board pages

Hardcodes the urls for the two boards and units
Update tests to revers to units instead of unit-lists
Tests added for board and advisory board
Remove email from board member listing

We should not make emails of board members available to visitors (but emails of
unit members are still available since that's "our" staff's work emails)
Merge pull request #50 from okfn/board-lists

Board and advisory council pages