Allow modification of a release if Content is empty (fix #2516)

Fixed gravatar url

Update Docker container with Alpine 3.3 & Fix RPi2 build

- Dockerfile.rpi now uses hypriot/rpi-alpine-scratch as base (build script are available w/ a better maintainer & more updates)
- Dockerfile.rpi updates alpine from v3.2 to v3.3 to be on par with Dockerfile

- Dockerfile now uses alpine:3.3 as base
- Dockerfile.rpi now uses v3.3/community repository without pinning
- Go package is no longer fetched using repository pinning
- Fixes problem while using repository pinning & virtual package at the same time

Split view fixed

- Change tooltip size from mini to tiny in profile page

Change user name in Pull Requests to avoid errors (fixes #2495)

Refactoring of inline diff computing to prevent empty diff box.

Fix grammar in deploy key section

Fixed Webhook URL-length Issue #2465

Add Docker Volume from 1.9

Add command to run the test suite in Makefile.

To add spanish translation to home template

Compute inline diff for pull request view, too. Fix #2462

Update Dockerfile & build script and add /etc/nsswitch.conf

Admins are allowed to create repos for arbitrary Orgs

[Feature] Markdown Checklist-rendering

Fix #2431 - handle requests waiting for reply

- Add nsswitch.conf to configure LibC Name Service inside the container
- Change my email in the Dockerfile
- Update build script to install software as a `build-deps` virtual package so that adding a package to it will be automatically	removed at the end of the build script

Fixed forgotten err variable assignment

According to the docs [1], the Reply method must be called for all
requests where WantReply is true. This fixes a hanging java ssh
implementation (jsch) which sets WantReply flag and waits for reply from
the server.

[1] https://godoc.org/golang.org/x/crypto/ssh#Request.Reply