Wrote missing chapter on securing object storage (Swift).

Provides detailed guidelines on network and service security.

Change-Id: I7f6f13f710f27b56a444b038d06ad07a680cfc20
Corrected link to VMware KB article

Rather than replace the link wholesale, I have restored
that link and added a paragraph that better describes the
need for the procedure described in the second KB article
(Pursuant to Andreas's comment in the review).

Change-Id: Ie1cc385254f726a37f01caaaceb531ad5c31ec91
backport: havana
Closes-Bug: #1259666
Merge "Corrected link to VMware KB article"
General updates to Compute for style and convention

Editing the top third of the compute chapter. Mostly grammar, wording,
style, convention, etc. Some minor section-level editing to improve
readability. Watch this space for more edits on these bugs.

Change-Id: If541f4a5e20251c94f6cbf416ff7c0d0e4c66892
Partial-Bug: #1251195
Partial-Bug: #1121866
Merge "General updates to Compute for style and convention"
Merge "Wrote missing chapter on securing object storage (Swift)."