Parsing TOML file And using Struct to Store

tutorials
1 
TOML File example: 
[[zone]]
abbr="GMT"
name="Greenwich Mean Time"
utcoffset="UTC0"
insec=0

[[zone]]
abbr="UTC"
name="Universal Time Coordinated"
utcoffset="UTC0"
insec=0

[[zone]]
abbr="ACDT"
name="Australian Central Daylight Savings Time"
utcoffset="UTC+10:30"
insec=37800

cargo.toml
...
[dependencies]
# libc = "*"
toml = "0.2"
rustc-serialize = "0.3.19"
...

Code:
extern crate toml;
extern crate rustc_serialize;

use std::env;
use std::fs;
use std::fs::{File, OpenOptions};
use std::io;
use std::io::prelude::*;
// use std::os::unix;
use std::path::Path;
use toml::Value;
use rustc_serialize::Decodable;
use rustc_serialize::Decoder;

#[derive(RustcDecodable,Debug)]
struct TZone {
      abbr      : Option<String>
    , name      : Option<String>
    , utcoffset : Option<String>
    , insec     : Option<u32>
}

#[derive(RustcDecodable,Debug)]
struct TZVec {
    zone    : Option<Vec<TZone>>
}

fn main() {
    // get Current Directory
    let cwd :String = match env::current_exe() {
          Ok(c) => c.display().to_string()
        , Err(e) => panic!("Error processing envirnment variable of current_exe dir - Err: {}!", e)
    };

    println!(">> Current Working Directory: {}", cwd);


    // Zones File
    let zone_file = "C:\\Users\\CBHATTARAM\\Workspace\\biff\\data\\zones.toml";

    let mut zhdl = match File::open(zone_file) {
        Ok(f) => f
        , Err(e) => panic!("Error occurred opening file: {} - Err: {}", zone_file, e)
    };

    let mut zstr = String::new();
    match zhdl.read_to_string(&mut zstr) {
          Ok(s) => s
        , Err(e) => panic!("Error Reading file: {}", e)
    };
    println!("Zone File: {}", zone_file);

    let tml :TZVec = toml::decode_str(&zstr).unwrap();
    for x in tml.zone.unwrap() {
        // println!("X: {:?}", x);
    }

    // Read Directory
}