Account database lock exception fixed (#1267)

* Accounts database lock exception fixed

Enable "Write-Ahead Logging" instead of a rollback journal when using SQLite - https://www.sqlite.org/wal.html

# Description
This fix solves bug with accounts going into cool down because of database locks wile reading.

# Motivation and Context
This fixed error #1232

# How Has This Been Tested?
This has been tested with 77 workers. The accounts stopped going into cool down.

# Types of changes
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

# Checklist
- [x] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.

* Update models.py

Solve problems with large pogom.db-wal file.

https://github.com/PokemonGoMap/PokemonGo-Map/pull/1267#issuecomment-246826983

* Correct a failure

* PEP8.

pogom/models.py

@@ -10,14 +10,15 @@
 import time
 import geopy
 import math
-from peewee import SqliteDatabase, InsertQuery, \
+from peewee import InsertQuery, \
     Check, CompositeKey, ForeignKeyField, \
     IntegerField, CharField, DoubleField, BooleanField, \
     DateTimeField, fn, DeleteQuery, FloatField, SQL, TextField, JOIN
 from playhouse.flask_utils import FlaskDB
 from playhouse.pool import PooledMySQLDatabase
 from playhouse.shortcuts import RetryOperationalError
 from playhouse.migrate import migrate, MySQLMigrator, SqliteMigrator
+from playhouse.sqlite_ext import SqliteExtDatabase
 from datetime import datetime, timedelta
 from base64 import b64encode
 from cachetools import TTLCache
@@ -58,8 +59,13 @@ def init_database(app):
             max_connections=connections,
             stale_timeout=300)
     else:
-        log.info('Connecting to local SQLite database...')
-        db = SqliteDatabase(args.db)
+        log.info('Connecting to local SQLite database')
+        db = SqliteExtDatabase(args.db,
+                               pragmas=(
+                                   ('journal_mode', 'WAL'),
+                                   ('mmap_size', 1024 * 1024 * 32),
+                                   ('cache_size', 10000),
+                                   ('journal_size_limit', 1024 * 1024 * 4),))
 
     app.config['DATABASE'] = db
     flaskDb.init_app(app)