Add "srcBasePath" feature to allow manipulating path when copying

Currently if I have my built files in "dist/*" and I want to SFTP them to "/server/*" there's no way to do this, they'll end up under "/server/dist/*".  This PR adds a "srcBasePath" option that will replace the contents of srcBasePath in the paths when building the destPath.  So specifying a srcBasePath of "dist/" above would correctly put the files into "/server/*"