Added support for display first and last pages and custom display title on next/previous

Example of usage:

@Html.Pager(...).Options(o => o.SetPreviousPageTitle("Previous
page").DisplayFirstAndLastPage().SetFirstPageTitle("Go to first page"))
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/MvcPaging.Demo/Areas/Area51/Views/Paging/Index.cshtml
Merge branch 'master' of https://github.com/nicollasricas/MvcPaging into nicollasricas-master
Something seems to have changed...?
Merge branch 'nicollasricas-master'
Updated Readme and one sample with the new options, see issue #41