Monthpicker

[dealfonso]

Proposed changes

materializecss includes a datepicker, but in some cases, we need to select only the month. This PR adds an attribute (monthPicker) to datetime to create pickers that display the months and years. Then the selected date will be day 1 of the month and year selected.

Screenshots (if appropriate) or codepen:

The screenshot for the new option:

A codepen that uses the new component can be found in this link

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).

Checklist:

• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.