- Previously the directory hierarchy was not clear regarding to which
  file belong to which part of the project (client or daemon).
  Further, we will have other clients in the future (such as Fuse).
- CMake files now differentiate between include dirs for all targets
  and target specific ones.
- Removed duplicate -pg flag.
- Not listing header files when adding executables or libraries
  is considered bad practice. Note that include_directories() is adding
  include paths to the code while adding all files used for executables
  and libraries provide the context which files belong to each binary.
  When only include_directories() is set, CMake assumes that all files
  belong to a binary (which is not necessarily true). As a result,
  some IDEs may break as the do not support this assumption.

  In general we should almost always favor explicitness over implicitness.

The preload specific cmake files inherits the global flag declarations,
thus it is not necessary to specify again all the flags.
Moreover the only addition made by this declaration is the `-fPIC` flag.
According to the official CMake docs [1], is set automatically for
library target as SHARED. Thus we don't need to set it explicitely.

[1]: https://cmake.org/cmake/help/v3.6/prop_tgt/POSITION_INDEPENDENT_CODE.html

Subprojects specific CMakeLists.txt inherits directives from the main cmake file.
Thus it is not necessary to replicate global level directives

since we use the `include_directories(include)` it is not necessary to
explitely specify all the headers file in the source list.

ADA-FS's statfs will fill the struct mostly with rough estimations.
It is not supposed to return accurate data but "some" data for applications to work

Added lseek64 syscall and used file flags properly

Users may use -DCMAKE_CXX_FLAGS_DEBUG to add addition compiler flags for debug mode.

The file position of a newly created OpenFile
it wasn't set correctly to 0.

See https://xgitlab.cels.anl.gov/sds/margo/issues/40 for reference of the issue.

Preload lib: RPC/IPC Mercury/Margo environments are only initialized if the mountdir path is used by the application
For that, the daemon writes the mountdir (it was started with) to a configurable path to disk.
The libraries read this value and only the process that uses part of this path will actually trigger the environment initialization.
This forbids prior behavior where applications initialize the whole environment numerous times, although unused.
For example, any MPI program will spawn multiple processes, all with the LD_PRELOAD environment variable set.

Configure file is split into a public and private part to distinguish file system configurations from monitoring, for example

Added: register daemon to system for storing auxiliary files + better daemon startup and shutdown handling