Add workaround for npm/uid-number#3

npm config set unsafe-perm true is called otherwise we get

    Error: could not get uid/gid
    [ 'nobody', 0 ]

    at .../uid-number/uid-number.js:37:16
    ...

error.

events/Dockerfile

@@ -10,8 +10,11 @@ COPY scripts/ /scripts/
 # Getting from branch master, they don't provide tags, or stable branch
 # https://github.com/taigaio/taiga-events/issues/8
 ADD https://github.com/taigaio/taiga-events/archive/${TAIGA_VERSION}.tar.gz /taiga_events/
+
+# See https://github.com/npm/uid-number/issues/3 for why the 'set unsafe-perm'
 RUN tar -xzf ${TAIGA_VERSION}.tar.gz -C ./ taiga-events-master/ --strip-components=1 \
     && rm ${TAIGA_VERSION}.tar.gz \
+    && npm config set unsafe-perm true \
     && npm i npm@latest -g \
     && npm install --production && npm install -g coffee-script \
     && addgroup -S taiga && adduser -S -G taiga taiga \