Expand and edit ES manual page

Adding new section on connecting Titan and secure Elasticsearch
clusters, updated many existing sections, including legacy-track
config examples, descriptions of interface-track config options, and
troubleshooting connections to remote ES clusters
Update descriptions on two ES ConfigOptions
Separate ES node/transport-specific options

Now TTL_INTERVAL is only considered by the Node client, and
CLIENT_SNIFF is only considered by the transport client
Documentation: add prev/next links to header

Both the fixed header and the floating/sticky header now have
chapter-previous and chapter-next links.  These links complement
rather than replace the existing links just above the copyright
footer.
doc CSS hack: make anchors offset by header height

Using intra-page anchor links with the documentation prior to this
commit was sort of clumsy, since the sticky/floating header at the top
of the viewport would obscure about the topmost ~85 pixels of whatever
the link jumped to -- usually the section header and an initial
sentence or two.

This CSS hack makes anchor links jump about 88 pixels too high to
compensate for the height of the floating/sticky header.
Update introductory Elasticsearch quote

The old quote is no longer listed on the ES homepage, so the
attribution link has rotten.  Updated with a similar (but current)
quote from the ES overview page.
Typos and prose edits in ES doc page
Update ES ConfigOption descriptions
Applying @rjbriody's documentation errata
Merge branch 'titan05' of github.com:thinkaurelius/titan into titan05