Writing to the users filesystem - addressing package development requirements

[jdeboer]

Currently, the following functions will need to be reviewed against those requirements:

• GoogleApiCreds
• GaMetaUpdate

[jdeboer]

The following package may be useful for addressing this requirement:
https://github.com/hadley/rappdirs

For example, see how this is used by the swirl package: https://github.com/swirldev/swirl

[jdeboer]

This issue may be made redundant by replacing the above mentioned functions with calls to their googleAnalyticsR counterparts. @MarkEdmondson1234

[jdeboer]

As per package development guidelines:
"Packages should not write in the users' home filespace, nor anywhere else on the file system apart from the R session's temporary directory (or during installation in the location pointed to by TMPDIR: and such usage should be cleaned up). Installing into the system's R installation (e.g., scripts to its bin directory) is not allowed.
Limited exceptions may be allowed in interactive sessions if the package obtains confirmation from the user.