Add convertType to WQP functions

[ldecicco-USGS]

Just like the NWIS functions, there should be an argument in the WQP functions to bring in everything as character instead of having dataRetrieval try to make the correct dates/numerics/etc.

[alkrall]

1. Added:

convertType=TRUE

if statement to importWQP. 2) Added convertType to function call in importWQP, readWQPdata, readWQPqw, whatWQPdata. 3) Set:

convertType=convertType 

to importWQP function call within readWQPdata, readWQPqw, and whatWQPdata. 4) Added reoxygen documentation to importWQP, readWQPdata, readWQPqw, whatWQPdata. 5) Added tests to testthat.R. -Test issues raised in whatWQPsamples and whatWQPmetrics with importWQP.