fix .git-ftp-ignore support for similar filenames

This fixes the bug (#41) where you have something like this in your .gitignore:

    foo.html:templates/foo.html

and foo.html will never be uploaded, because git-ftp was just doing a string
search through the list of files already being uploaded (which included
"templates/foo.html") and assumed that all substring matches mean that
"foo.html" is already being uploaded.

This is fixed by reading the files with bash read loops, and checking whole
lines and substrings in bash (instead of using grep.)