CHERKASY-18 Removal of previous project files

As tranSMART's database is accessed in a completely different way (via
RESTful API calls instead of direct SQL queries), and the desired
functionality has been changed as well, all current functions
are obsolete and need to be rewritten, hence their removal.
CHERKASY-63 Initial commit of new transmart R client

This initial work contains the preliminary functionality needed in the
new transmart R client. It contains a simple re-direct oauth flow, as
well as two working functional calls (getStudies and getSubjects).
Seperated oauth authorization from connection method

Testing is done without oauth, therefore it was necessary to enable a
connection to the RESTful API without any authorization.
Some small text improvements
Added R documentation for available functions
Added option to convert results to data.frame

Results are by default returned as a list, which is more robust, but is
a very cumbersome R data object to work with. Therefore, I added an
option to convert this list into a data.frame.
Added the getObservations call
Added documentation for getObservations

Also updated documentation for other functions
Optional OAuth http header was not properly appended
Added licensing information
Added connection status functionalities; ping and error

The connection can now be pinged before each call, to test the status of
the connection. If there is an error, it is caught and returned in a
user friendly way.
Typo in argument, should be defined as string
Some additional documentation and cleanup
Corrected some typos
Added dependencies on other packages
Changed base URL mapping

Due to the RESTapi now being an inline plugin of transmartAPP
instead of being in its own module
Changed default client id and secret values
Bugfix in check whether access token already exists
Added connection status check
Removed use of development environment in devCommand.R

Included manual package re-load command instead, as the previous method
was not as reliable as I had hoped. Also included some other small
changes.