Explicit include string.h in KTRSAMATReader.cc

I had to add a include string.h in KTRSAMATReader.cc to make it work on
a gentoo system.
Removed -std=c++11 flag from the compiler options

I had added the flag “-std=c++11” to the compiler because it was
required by matlab to link properly with its libraries.  Turns out that
it causes conflicts with boost in other installs, and that we can
compile Katydid+Matlab without it, so we removed it.