Fixing compilation on GCC 4.7.2 on Ubuntu 12.04

Hi, 

I wasn't able to compile library on my ubuntu 12.04 with GCC 4.7.2, so I've fixed it. 
If you find this tiny patch to be useful please apply. 

Also I've provided installation possibility (normally via make install). This is somehow connected with https://github.com/glynos/uri/pull/15

BR, 
w0land