dashboard: rename Go14URL to goBootstrapURLTmpl and provide accessor

Also update all users, and rename another template field.
Includes changes to coordinator, gomote, and release.

Change-Id: I1c4408eadbcb83d61063a910dfa18cc395952bc2
Reviewed-on: https://go-review.googlesource.com/20976
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
6 files changed