Add initial module structure

libimagtag/src/lib.rs

@@ -1,2 +1,12 @@
 extern crate regex;
 extern crate toml;
+
+extern crate libimagstore;
+
+pub mod add;
+pub mod check;
+pub mod error;
+pub mod remove;
+pub mod result;
+pub mod tag;
+pub mod util;

libimagtag/src/tag.rs

@@ -0,0 +1 @@
+pub type Tag = String;

libimagtag/src/util.rs

@@ -0,0 +1,5 @@
+use regex::Regex;
+
+pub fn is_tag(s: &String) -> bool {
+    Regex::new("^[a-zA-Z]([a-zA-Z0-9_-]*)$").unwrap().captures(&s[..]).is_some()
+}