Add configurable password strength policy

src/main/resources/application.properties

@@ -7,6 +7,8 @@ spring.jpa.hibernate.ddl-auto=update
 # for jwt
 app.jwt.secret=${JWT_SECRET:ChangeThisSecretKeyForJwt}
 app.jwt.expiration=${JWT_EXPIRATION:86400000}
+# Password strength: LOW, MEDIUM or HIGH
+app.password.strength=${PASSWORD_STRENGTH:LOW}
 
 # Post publish mode: DIRECT or REVIEW
 app.post.publish-mode=${POST_PUBLISH_MODE:DIRECT}