How to sync a forked repository with original repository in Github ?

for creating another branch synced with original repo:

git remote add upstream https://github.com/account/repository.git
git fetch upstream
git merge upstream/master upstream
git rebase upstream/upstream

For

$ git remote add upstream https://github.com/account/repository.git
$ git fetch upstream

# then: (like "git pull" which is fetch + merge)
$ git merge upstream/master master

# or, better, replay your local work on top of the fetched branch
# like a "git pull --rebase"
$ git rebase upstream/master

How to update slimerjs to 0.10 or newer which is installed via npm install slimerjs ?

If you came across this issue like me here is how to update slimerjs:

npm install -g slimerjs
cd /usr/local/lib/node_modules/slimerjs/lib/
mv slimer slimerjs-bak
wget http://download.slimerjs.org/releases/0.10.0/slimerjs-0.10.0.zip
unzip slimerjs-0.10.0.zip
mv slimerjs-0.10.0/ slimer

with new v10.0 you need to update your firefox version too. you can choose a version between 42 and 46.