Add a Dockerfile

This is not a perfect Dockerfile, but is a perfect base for anyone willing to run PrivateBin
inside a container. There are a lot of ways to improve it, first being "having configuration
in environment variables".
Anyway, this Dockerfile is great as a basis, and it is possible to "fork" the image and add
our own config file into it.
Another improvement might be "adding a docker-compose.yml full stack, with mysql+bin".

Feel free to do it \o/

Dockerfile

@@ -0,0 +1,17 @@
+FROM php:apache
+
+RUN apt-get update && apt-get install -y \
+        libfreetype6-dev \
+        libjpeg62-turbo-dev \
+        libpng12-dev \
+        wget \
+        zip \
+        unzip; \
+    # We install and enable php-gd
+    docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/; \
+    docker-php-ext-install -j$(nproc) gd; \
+
+    # We enable Apache's mod_rewrite
+    a2enmod rewrite
+
+COPY . .