Use sourceforge on HTTPS (#280)

* Use sourceforge on HTTPS

* Remove dependency on the evil sourceforge
diff --git a/Dockerfile b/Dockerfile
index 918bf3f..ab0b142 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -64,7 +64,7 @@
 
      && cd /tmp/api-gateway/ \
      && curl -k -L https://github.com/nbs-system/naxsi/archive/${NAXSI_VERSION}.tar.gz -o /tmp/api-gateway/naxsi-${NAXSI_VERSION}.tar.gz \
-     && curl -k -L http://downloads.sourceforge.net/project/pcre/pcre/${PCRE_VERSION}/pcre-${PCRE_VERSION}.tar.gz -o /tmp/api-gateway/pcre-${PCRE_VERSION}.tar.gz \
+     && curl -k -L https://ftp.pcre.org/pub/pcre/pcre-${PCRE_VERSION}.tar.gz -o /tmp/api-gateway/pcre-${PCRE_VERSION}.tar.gz \
      && curl -k -L https://openresty.org/download/openresty-${OPENRESTY_VERSION}.tar.gz -o /tmp/api-gateway/openresty-${OPENRESTY_VERSION}.tar.gz \
      && tar -zxf ./openresty-${OPENRESTY_VERSION}.tar.gz \
      && tar -zxf ./pcre-${PCRE_VERSION}.tar.gz \