Fix "directory exists" test failures when setting up nginx

Some versions of nginx create directories, so use -p with mkdir.

test/Dockerfile-bash4-0

@@ -7,9 +7,9 @@ RUN apk --no-cache add supervisor openssl git curl bind-tools drill wget nginx l
 WORKDIR /root
 
 # Create nginx directories in standard places
-RUN mkdir /run/nginx
-RUN mkdir /etc/nginx/pki
-RUN mkdir /etc/nginx/pki/private
+RUN mkdir -p /run/nginx
+RUN mkdir -p /etc/nginx/pki
+RUN mkdir -p /etc/nginx/pki/private
 
 # Setup ftp
 ENV VSFTPD_CONF=/etc/vsftpd.conf

test/Dockerfile-bash4-2

@@ -7,9 +7,9 @@ RUN apk --no-cache add supervisor openssl git curl bind-tools drill wget nginx l
 WORKDIR /root
 
 # Create nginx directories in standard places
-RUN mkdir /run/nginx
-RUN mkdir /etc/nginx/pki
-RUN mkdir /etc/nginx/pki/private
+RUN mkdir -p /run/nginx
+RUN mkdir -p /etc/nginx/pki
+RUN mkdir -p /etc/nginx/pki/private
 
 # Setup ftp
 ENV VSFTPD_CONF=/etc/vsftpd.conf

test/Dockerfile-bash5-0

@@ -7,9 +7,9 @@ RUN apk --no-cache add supervisor openssl git curl bind-tools drill wget nginx l
 WORKDIR /root
 
 # Create nginx directories in standard places
-RUN mkdir /run/nginx
-RUN mkdir /etc/nginx/pki
-RUN mkdir /etc/nginx/pki/private
+RUN mkdir -p /run/nginx
+RUN mkdir -p /etc/nginx/pki
+RUN mkdir -p /etc/nginx/pki/private
 
 # Setup ftp
 ENV VSFTPD_CONF=/etc/vsftpd.conf

test/Dockerfile-centos7-dynu

@@ -17,8 +17,8 @@ ENV dynamic_dns "duckdns"
 #ENV DYNU_API_KEY 
 
 WORKDIR /root
-RUN mkdir /etc/nginx/pki
-RUN mkdir /etc/nginx/pki/private
+RUN mkdir -p /etc/nginx/pki
+RUN mkdir -p /etc/nginx/pki/private
 COPY ./test/test-config/nginx-ubuntu-no-ssl /etc/nginx/conf.d/default.conf
 COPY ./test/test-config/nginx-centos7.conf /etc/nginx/nginx.conf