Build system

• switch to CMake
• OSX build improvements, RPATH setup

Dependencies

• Drop Boost dependency. Uses tinyxml2 to read existing XML config archives.
• Drop librlog dependency. Uses easylogging++ for logging.

FUSE and FreeBSD updates

• add encfs_create operation
• replace getdir with readdir

Misc

• cleanup includes and reformat code
• allow writes in reverse mode when no header is used
• make use of C++11 (eg std unordered_map in place of GNU internal hashmap)