Add .tgz to the compressed file extensions

Fixes #129

Vagrantfile

@@ -90,6 +90,7 @@ Vagrant.configure("2") do |config|
 
         touch "#{test_dir}/file-types/compressed.zip"
         touch "#{test_dir}/file-types/compressed.tar.gz"
+        touch "#{test_dir}/file-types/compressed.tgz"
 
         touch "#{test_dir}/file-types/backup~"
         touch "#{test_dir}/file-types/#SAVEFILE#"

src/info/filetype.rs

@@ -66,7 +66,7 @@ impl<'a> File<'a> {
     pub fn is_compressed(&self) -> bool {
         self.extension_is_one_of( &[
             "zip", "tar", "Z", "gz", "bz2", "a", "ar", "7z",
-            "iso", "dmg", "tc", "rar", "par"
+            "iso", "dmg", "tc", "rar", "par", "tgz",
         ])
     }
 

xtests/file-types

@@ -6,6 +6,7 @@ compiled.coffee
 compiled.js
 compiled.o
 compressed.tar.gz
+compressed.tgz
 compressed.zip
 crypto.asc
 crypto.signature