Add Windows package script
Don't register with an existing username

Register method has been modified. A new user cannot register with an existing username.
Prompt error if username is already taken

Add onFailure to prompt an error about that a username is taken
Update DataServiceImpl.java
Merge pull request #146 from khfayzullaev/master

Don't register with an existing username
Admin cannot add a user with an existing username
Alert a message if admin adds an existing username
Update SettingsController.java
Merge pull request #147 from khfayzullaev/master

Admin should not add an existing username
Prevent adding devices with the equal Unique IDs
Prevent adding devices with the equal Unique IDs
Update DataServiceImpl.java
Update DeviceController.java
Update DataServiceImpl.java
Update DataServiceImpl.java
Merge pull request #2 from khfayzullaev/patch-1

Merging Patch 1
Update DataServiceImpl.java
Update DataServiceImpl.java
Update DataServiceImpl.java
Update DataServiceImpl.java