Add peewee ext

Author: laodouya

pycovenantsql/__init__.py

@@ -15,7 +15,7 @@
 
 threadsafety = 1
 apilevel = "2.0"
-paramstyle = "pyformat"
+paramstyle = "format"
 
 
 class DBAPISet(frozenset):

pycovenantsql/ext/peewee.py

@@ -0,0 +1,14 @@
+import pycovenantsql
+from peewee import Database, ImproperlyConfigured
+
+class CovenantSQLDatabase(Database):
+    param = '%s'
+    quote = '``'
+    def __init__(self, database, **kwargs):
+        super(CovenantSQLDatabase, self).__init__(database, **kwargs)
+
+    def _connect(self, **kwargs):
+        if pycovenantsql is None:
+            raise ImproperlyConfigured('pycovenantsql driver not installed!')
+        conn = pycovenantsql.connect(database=self.database, **self.connect_params)
+        return conn