calculus - Computing the limit of an integral sequence

I've been trying for the last few hours to solve the following problem, which looks like this :

Find the limit $l$ : $$l=\mathop {\lim }\limits_{n \to \infty } \,\,\,n\int\limits_0^n {\frac{{\arctan (\frac{x}{n})}}{{x(x^2 + 1)}}} \,dx$$

Use the result to compute: $$\mathop {\lim }\limits_{n \to \infty } \,\,\,n\,(\,n\int\limits_0^n {\frac{{\arctan (\frac{x}{n})}}{{x(x^2 + 1)}}} \,dx - \frac{\pi }{2})$$
I've tried Taylor expansion, partial fraction decomposition, but I can't really find anything useful. Some help would be really appreciated. I'm much more interested in the method than in the actual result.