Saving token for authentication
 - Instead of storing username/password onto pom or settings.xml
 - token will be stored in the user's home directory as .mvn-cf.xml
 - 2 new goals have been added. Login and Logout
 - Login goal will create the token file and also do the initial login
 - Logout will delete the token file and logout the user

Change-Id: Ifa13af764f107fa909d51381f906d5e83a262a64