Add skeleton of for DataStore
Added pugixml
Enable pugixml support for wchar_t
Remove nonsense DEFAULT_DESCRIPTION and rename DEFAULT_TIME to DEFAULT_DEADLINE
Add the setters
Rename class Storage to DataStore, include boost, and create constructor and destructor
Implement task_model

* Builder now easy to use by taking advantage of move assignment operator
  from the Task directly. For example,

	Task task = Task::Builder::description("Hello World")
				  .deadline(tomorrow());

* Creating a task with empty description is an exception.

* General improvement.
Link with project properly
Change to multiple builders

* After some discussion, it is decided that we use many instances
  of builder instead of singleton builder building single task at
  a time.
Line spacing edit.
Add user file to tracking first.
Delete user file.
Deleted pro file.
Updated GUI appearance.
Updated documentation.
Add pugixml as submodule instead of a part of DataStore
Changes to vcxproj and sln files, change include directory in datastore.h for pugixml
Remove git submodule, fix lint warnings
Modify cpplint to ignore pugixml
Add pugixml submodule (my fork, not the real one)