Remove ^ from tag regex in tasks

This prevented tags in a comma list from being considered and removed
from the excerpt.

related to #1010

GTG/core/tasks.py

@@ -43,7 +43,7 @@
 # REGEXES
 # ------------------------------------------------------------------------------
 
-TAG_REGEX = re.compile(r'^\B\@\w+(\-\w+)*\,*')
+TAG_REGEX = re.compile(r'\B\@\w+(\-\w+)*\,*')
 SUB_REGEX = re.compile(r'\{\!.+\!\}')