Adds $opt argument to get* methods.

Current version of Asana API supports options for most GET calls.
This commit adds $opt as an argument to the following methods:

- getUserInfo()
- getTask()
- getSubTasks()
- getProjectsForTask()
- getTaskStories()
- getProject()
- getProjects()
- getProjectTasks()
- getProjectStories()
- getTag()
- getTasksWithTag()
- getSingleStory()
- getWorkspaceTasks()
Merge pull request #15 from ericthelast/feature/add-options-to-get-methods

Adds $opt argument to get* methods.