Replace non-ascii symbols in docs

In order to successfully run sphinxcontrib-spelling on Ceilometer docs we need
to replace all non-ascii symbols with the analogous ones from ascii.

Without this fix sphinxcontrib-spelling will fail with:
"UnicodeEncodeError: 'ascii' codec can't encode character u'\u2019'
in position 8: ordinal not in range(128)"

Change-Id: I37891b9471571c3509aece3949d9593738f99849
Fixing some simple documentation typos

Change-Id: If32dead1f42e21db9c556ba1199a24fc6f18da0b
Closes-Bug: 1277224
Merge "Fixing some simple documentation typos"
Merge "Replace non-ascii symbols in docs"