+ added file_info.h
* added some comments.
+ added more comments.
+ added file_info.cpp.
* modified Makefile.am.
+ added copy constructor.
+ added move constructor.
+ added assign operator.
+ added release function.
+ added FileInfo& FileInfo::operator=(FileInfo&& rhs)
Merge pull request #9 from vsfs/add_file_info_and_op

Add file info class
Merge branch 'master' into index_path_map