Binary Environment (#256)

Adds a fission environment for arbitrary linux binaries.

environments/binary/README.md

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+# Binary Environment Examples
+
+The `binary` runtime is a go server that uses a subprocess to invoke executables or execute shell scripts.
+
+Use Cases
+- Execute bash scripts
+- Run executables of languages that have no dedicated environment yet.
+
+## Words of Caution
+The environment runs on an alpine image with some additional utilty commandline tools installed, such as 'grep'. 
+However, in case you want to make use of more ecsoteric commandline tools, you should add the relevant apk to the 
+Dockerfile and build a new binary environment. See 'Compiling' for instructions.
+
+When executing functions using binaries, **ensure that the executable is built for the right architecture**. 
+Using the default binary environment this means that the binary should be build for Linux.
+
+## Usage
+The interface to the executable used by this environment is somewhat similar to a [CGI interface](https://en.wikipedia.org/wiki/Common_Gateway_Interface).
+This means that any HTTP headers are converted to environment variables of the form "HTTP_<header-name>". For example these
+are some of frequently occurring headers:
+
+```
+# Request Metadata
+CONTENT_LENGTH
+REQUEST_URI
+REQUEST_METHOD
+
+# HTTP Headers
+HTTP_ACCEPT
+HTTP_USER-AGENT
+...
+```
+
+The body of HTTP piped over the STDIN to the executable. 
+All output that is provided to the server over the STDOUT will be transformed into the HTTP response.
+
+
+## Compiling
+In order to build the Dockerfile, the server needs to be compiled to the right architecture.
+
+```bash
+sh ./build.sh
+```
+
+Build the Dockerfile:
+```bash
+docker build --tag=${USER}/binary-env .
+```
+
+See the [README](../../examples/binary/README.md) in the binary examples directory for usage instructions.