Use anyhow for error handling

Summary:
This is a nice solution if you don't want to spend
too much time thinking about error handling.
You have one common return type and can basically use `?`
everywhere while still maintaining the flexibility to
create custom error types where needed.

Reviewed By: jknoxville

Differential Revision: D21349046

fbshipit-source-id: 073539ce8422cdb3e0141886e95321052bc0c7a3

packer/Cargo.lock

@@ -9,6 +9,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9a60d744a80c30fcb657dfe2c1b22bcb3e814c1a1e3674f32bf5820b570fbff"
+
 [[package]]
 name = "arrayref"
 version = "0.3.6"
@@ -143,6 +149,7 @@ dependencies = [
 name = "flipper-packer"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "clap",
  "serde",
  "serde_yaml",