base path for compilation can be './' as well as '.'

Hi, this is a fix for unexpected behaviour when compiling with the -c switch and './' value. See below, please. Thanks.

When coffee is invoked with the -c parameter and './' value, first two characters of the directory into which the compiled files are stored get chopped off.
Example: if compilation invoked like this: 'coffee -o ../lib/ -cw ./', then
Source file: ./OutputFolder/file.coffee, compiled output: ./../lib/tputFolder/
The code only expected '.' to mark the local folder. However, './' is equally valid.