Fix issue #14

Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get update && \
 apt-get install -y software-properties-common && \
 nginx=development && \
 add-apt-repository ppa:nginx/$nginx && \
+apt-get update && \
 apt-get upgrade -y && \
 BUILD_PACKAGES="supervisor nginx php5-fpm git php5-mysql php5-mysql php-apc php5-curl php5-gd php5-intl php5-mcrypt php5-memcache php5-sqlite php5-tidy php5-xmlrpc php5-xsl php5-pgsql php5-mongo pwgen" && \
 apt-get -y install $BUILD_PACKAGES && \