Added all the necessary to do GetLanguageByAlias functionality works

internal/code-generator/assets/aliases.go.tmpl

@@ -0,0 +1,13 @@
+package slinguist
+
+// CODE GENERATED AUTOMATICALLY WITH gopkg.in/src-d/simple-linguist.v1/internal/code-generator
+// THIS FILE SHOULD NOT BE EDITED BY HAND
+// Extracted from github/linguist commit: {{ getCommit }}
+
+// languagesByAlias keeps alias for different languages and use the name of the languages as a alias too. All the
+// keys (alias or not) are written in lower case and the whitespaces has been replaced by underscores.
+var languagesByAlias = map[string]string{
+	{{range $alias, $language := . -}}
+	"{{ $alias }}":	{{ printf "%q" $language -}},
+	{{end -}}
+}