Correct the num of pages when total_posts exactly equals to per_page

Also fix the active page in paginator_navigation

Before the fix, I got errors as below:
2013/03/04 00:03:28 compile.go:589: 3 /posts/ paginator 4
2013/03/04 00:03:28 compile.go:592: page number = 1
2013/03/04 00:03:28 compile.go:592: page number = 2
2013/03/04 00:03:28 compile.go:592: page number = 3
2013/03/04 00:03:28 compile.go:592: page number = 4
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac00
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac00
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac40
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac40
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac80
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 node.go:88: What? 0xf8401cac80
2013/03/04 00:03:28 node.go:88: What? 0xf8401cacc0
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2013/03/04 00:03:28 context.go:228: Not Support kind=func
2