Remove comment on projection information

Comment was no longer relevant.
Add code to get PROJ.4 string from EPSG code input
Set codeblock as a function

Reconfiguring the code in the chunk reserved for the
'define.calmet.domain' function, as a function.
Set defaults for the function and renamed variables
to adhere to the dot-naming convention.
Add require statements for R packages
Fix comment spacing and correct object name
Merge branch 'master' of https://github.com/rich-iannone/PuffR