cmd/fscrypt: Initial stub program and docs

This commit adds in a stub fscrypt program. The binary just tells the
time and the tests do nothing, but the Makefile will build them! This
commit also adds documentation to the README that explains how to get,
build, run, test, format, lint, and install the code.

Also note that the executable is now in the cmd/fscrypt directory. The
library implementing the core functionality will be at the root. This
is essentially point 2 of https://medium.com/@benbjohnson/structuring-applications-in-go-3b04be4ff091

Change-Id: Ib7bd782e458bdf3db456beb978be4c75b4734561

1 files changed, 34 insertions, 7 deletions

diff --git a/README.md b/README.md
index c6bfa6a..37497a4 100644
--- a/README.md
+++ b/README.md
@@ -55,18 +55,31 @@ background. `fscrypt` has a [design document](https://goo.gl/55cCrI) that
 discusses many of the higher level design choices that were made.
 
 Specifically, `fscrypt` contains the following functionality:
-*   TODO
+*   Telling the time (but this is a stub program)
 
 ## Building
 
-<!-- TODO: Change git clone URL before public release -->
-Get the source by running `git clone [REDACTED] fscrypt`.
-You need to [setup your `GOPATH`](https://golang.org/doc/code.html#GOPATH) and
-clone the repository into `$GOPATH/src/fscrypt`.
+`fscrypt` is written in Go, so to build the program you will need to
+[setup Go](https://golang.org/doc/install),
+[setup your `GOPATH`](https://golang.org/doc/code.html#GOPATH), and clone the
+repository into the correct location by running
+```shell <!-- TODO: Change git clone URL before public release -->
+git clone [REDACTED] $GOPATH/src/fscrypt
+```
+You will also want to add `$GOPATH/bin` to your `$PATH`.
+
+Once this is setup, you can run `make fscrypt` to build the executable in
+`build/fscrypt`. The only other build dependencies are `make` and a C compiler.
+Pass `"LDFLAGS += -static"` to `make` to get a static executable. If a Go
+project contains C code, the go compiler produces a dynamically linked binary by
+default.
 
 ## Running and Installing
 
-TODO
+`fscrypt` is a standalone binary, and it currently has no runtime dependencies.
+Installing it just requires placing it in your path or running `make install`.
+Change `$GOBIN` to change the install location of `fscrypt`; by default it is
+installed to `$GOPATH/bin`.
 
 ## Example Usage
 
@@ -74,7 +87,21 @@ TODO
 
 ## Contributing
 
-TODO
+If you are making changes to the `fscrypt` component, you will need the
+following additional commands:
+*   `make go` - Checks that all the go files build and tests pass.
+*   `make format` - Formats all of the go code.
+*   `make lint` - Checks the code for style errors, requires
+    [`golint`](https://github.com/golang/lint) to be installed.
+*   `make all` - Does the above three commands and builds `fscrypt`.
+
+Make sure that `$GOPATH/bin` is in you `$PATH`. All the above dependencies can
+be installed with:
+```bash
+> go get -u github.com/golang/lint/golint
+```
+
+These commands should be run before submitting any changes.
 
 ## Known Issues