update get_epchc_wq with timestamp check to download about tbeptools

[bbest]

We can use code like the following to check date stamp on the server:

library(curl)
library(stringr)

con <- curl("ftp://ftp.epchc.org/EPC_ERM_FTP/WQM_Reports/")
dat <- readLines(con)
close(con)
dat

returns the following so still need to parse line 7 to check current file with file.info():

 [1] "06-08-17  08:38AM                58625 2017StationListParametersSampled.xlsx"                   
 [2] "02-04-19  12:15PM       <DIR>          2018"                                                    
 [3] "06-11-19  01:15PM       <DIR>          2019"                                                    
 [4] "06-11-19  07:55AM              8475361 Backup of PlanktonDataList_ThroughCurrentReportMonth.xlk"
 [5] "01-31-19  12:15PM       <DIR>          Maps"                                                    
 [6] "06-11-19  07:59AM              8475416 PlanktonDataList_ThroughCurrentReportMonth.xlsx"         
 [7] "06-11-19  12:44PM             24401100 RWMDataSpreadsheet_ThroughCurrentReportMonth.xlsx"       
 [8] "01-08-19  09:30AM                51776 RWMPreliminaryData-Nov-Dec2018.xlsx"                     
 [9] "02-05-19  09:15AM       <DIR>          StationListsWithDescriptions"                            
[10] "08-10-16  10:52AM             39800639 Surface Water Quality 2001-2010_Final.pdf"               
[11] "08-27-07  09:48AM             51211894 Surface Water Quality HC 98-00.pdf"                      
[12] "01-09-18  02:41PM               102400 Thumbs.db"                        

[fawda123]

854ca79 Added a separate read_chkdate() function, used internally within get_epchc_wq()