added yml/json/toml support, --help flag, and example directory

Signed-off-by: Andrey Nering <andrey.nering@gmail.com>

example/Taskfile.json

@@ -0,0 +1,11 @@
+{
+  "hello": {
+    "cmds": [
+      "echo \"I am going to write a file named 'output.txt' now.\"",
+      "echo \"hello\" > output.txt"
+    ],
+    "generates": [
+      "output.txt"
+    ]
+  }
+}

example/Taskfile.yml

@@ -0,0 +1,6 @@
+hello:
+  cmds:
+    - echo "I am going to write a file named 'output.txt' now."
+    - echo "hello" > output.txt
+  generates:
+    - output.txt