Month is not highlighted when the date is not the first day of the month.

[ywangxpo]

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Current behavior
Calendar view is Month. When the date is not the first day of the month, the month is not highlighted.

Expected behavior
When the date is not the first day of the month, the month should be highlighted. For example, if the date is Aug 31st, 2018, Aug should be highlighted.

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?
bug.

Please tell us about your environment:

• Angular version: 6.1.2

• PrimeNG version: 6.1.0

• Browser: All browsers where this could be reproduced

• Language: all

• Node (for AoT issues): node --version =