Add -fPIC option for 64 bit linux machine compatibility.

:-1: error: /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libdartd.a(UtilsRotation.cpp.o): relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC
Fix code style.
Add -fPIC to CMAKE_CXX_FLAGS.
Merge pull request #72 from dartsim/64_bit_compatibility

Add -fPIC option for 64 bit linux machine compatibility.