go.blog: tidy up sidebar

The sidebar in individual article view is unwieldy.
Remove related articles, Google Developers links (that nobody clicks),
and remove the heading about the "Article index" link.

LGTM=dsymonds
R=dsymonds
CC=golang-codereviews
https://golang.org/cl/120870044
go.blog/context: don't use the address of an empty struct as a context
key, as this is not guaranteed to be unique.

Fixes golang/go#8443.

LGTM=campoy
R=adg, campoy
CC=dsymonds, golang-codereviews
https://golang.org/cl/121890043
go.blog: fix error in Laws of Reflection article

LGTM=dave
R=r, dave
CC=golang-codereviews
https://golang.org/cl/116440043
go.blog: fix build errors

Exclude these two files from the build

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/126760044
go.blog/context: userip support for IPv6 host/port.

Makes example usable on IPv6 systems eg where localhost is ::1.

Fixes golang/go#8486.

LGTM=adg
R=golang-codereviews, dave, adg
CC=golang-codereviews, sameer
https://golang.org/cl/117530044
go.blog: exclude gorilla example (fixes build)

Fix the build on builders that do not have git installed.

See discussion: https://groups.google.com/forum/#!topic/golang-dev/SAv_H7fJHkw

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/124890043
go.blog: add oscon report post

LGTM=adg
R=adg, campoy
CC=golang-codereviews
https://golang.org/cl/127570043
go.blog: fixing typo in oscon report blog post

LGTM=crawshaw
R=r, adg, crawshaw
CC=golang-codereviews
https://golang.org/cl/130330043
go.blog: fix spelling.

LGTM=campoy
R=golang-codereviews, gobot, campoy
CC=golang-codereviews
https://golang.org/cl/128490044
go.blog: constants

LGTM=gri, adg, rsc
R=gri, adg, rsc
CC=golang-codereviews
https://golang.org/cl/125540043
go.blog: s/./,/ in constants blog post

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/129630043
go.blog: more glitches in constants post
All inconsequential.

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/130540043
go.blog/constants: use a format with Printf
Otherwise the prose around this snippet is confusing.

LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/130550043
go.blog: fix typo on constants blog post

LGTM=adg
R=adg, r
CC=golang-codereviews
https://golang.org/cl/133910043
go.blog: fix links in "Introducing Gofix"

Fixes golang/go#8692.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/141420043
go.blog: add Docker article

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/148190043
go.blog: add link to Docker blog

LGTM=crawshaw
R=golang-codereviews, crawshaw
CC=golang-codereviews
https://golang.org/cl/145460043
go.blog: update image name in Docker article

The listed image suffers from the "shellshock" bash bug.

LGTM=crawshaw
R=golang-codereviews, crawshaw
CC=golang-codereviews
https://golang.org/cl/150240043
go.blog: Report Go at Google I/O 2014

LGTM=adg
R=adg, campoy
CC=golang-codereviews
https://golang.org/cl/154920043
go.blog: use new golang.org/x/... import paths

TBR=rsc
R=rsc, r
CC=golang-codereviews
https://golang.org/cl/170250043