Name abbreviation

Return an abbreviation of the given string.

Sample Code:

function abbName(str) {
// Enter your logic here...
}

Examples:

Input: 'human being'
Output: 'H.B'
Explanation: Capitalized first letters separated by a dot. 

Input: 'Batman the Suparman'
Output: 'B.T.S'
Explanation: Capitalized first letters separated by a dot.