Fixed html block tags with numbers in name, closes #74

lib/rules_block/html_block.js

@@ -6,8 +6,8 @@
 var block_names = require('../common/html_blocks');
 
 
-var HTML_TAG_OPEN_RE = /^<([a-zA-Z]{1,15})[\s\/>]/;
+var HTML_TAG_OPEN_RE = /^<([a-zA-Z][a-zA-Z0-9]{0,14})[\s\/>]/;
-var HTML_TAG_CLOSE_RE = /^<\/([a-zA-Z]{1,15})[\s>]/;
+var HTML_TAG_CLOSE_RE = /^<\/([a-zA-Z][a-zA-Z0-9]{0,14})[\s>]/;
 
 function isLetter(ch) {
   /*eslint no-bitwise:0*/