this will allow for an easier upgrade/downgrade of yarn, e.g:
```
FROM node:6-slim
ENV YARN_VERSION 1.5.1
RUN curl -fSLO --compressed
"https://yarnpkg.com/downloads/$YARN_VERSION/yarn-v$YARN_VERSION.tar.gz"
&&\
tar -xzf yarn-v$YARN_VERSION.tar.gz -C /opt/ &&\
ln -snf /opt/yarn-v$YARN_VERSION /opt/yarn &&\
rm yarn-v$YARN_VERSION.tar.gz
```
* Update list of gpg keys
from https://github.com/nodejs/node#release-team
The former first key no longer seems to exist on the keyservers.
* Update gpg keys in other templates
- Add an architectures file to list supported architectures and
variants.
- Add new `ARCH` ENV into Dockerfile. It represents the architecture.
- Add a functions.sh to put utility functions, including
- get_arch: get the current running architecture.
- get_variants: get corresponding supported variants based on the
running architecture.
Signed-off-by: Yihong Wang <yh.wang@ibm.com>
If ha.pool.sks-keyservers.net times out we try pgp.mit.edu then
keyserver.pgp.com.
This should hopefully resolve the occasional build errors we see in
Travis and for issues like #340
Eyal Zekaria