check if root was build with c++11, if so, build root_numpy with c++11

[maxnoe]

I added a call to root-config --cflags to check if root was build with c++11 features and if this is the case -std=c++11 is added to the extra-compile-args for librootnumpy.

[coveralls]

Coverage remained the same at 100.0% when pulling f3166ea on MaxNoe:master into b400760 on rootpy:master.

[ndawe]

This is already done in #165 but there are still bugs in ROOT 6 that are causing crashes.

[ndawe]

We are waiting for ROOT devs to fix the bugs in ROOT 6 before merging #165.

[kratsg]

Should this be closed as duplicate issue? #165 certainly fixes it. In the mean time, they can edit their installation locally and reinstall.

[ndawe]

Yes, let's close this.

[ndawe]

@maxnoe sorry for closing this! We implemented the same thing a few weeks ago but then hit a bunch of problems in ROOT 6 that need to be fixed before root_numpy can be used there.