Support no `v-model` binding

Fix active page not changing caused by no v-model binding.

v2.0.1

Fix: Not go to prev page when the first page is selected.

v2.0.0

Feature: Use v-model to bind the current page number and remove initial-page.

v1.9.5

Feature: Support HTML string for prev and next button and remove slot support for them.

v1.9.4

Feature: Support HTML string for first and last button

v1.9.3

Fix: select correct page when click first and last button.

v1.9.2

Not called first and last page function when already selected.

v1.9.1

When first or last page is selected, the tabindex of 'next','prev','first page' and 'last page' buttons should be -1. To prevent focusing the elements via tabulation. #78

v1.9.0

Customize the breakView by slot

v1.8.0

Modify page range and update documentation