Handle the case where the path to the configuration file is framed by quotes

[yruslan]

Hi!

Currently, ENCFS5_CONFIG/ENCFS6_CONFIG environment variables cannot be used in Windows to store ".encfs6.xml" file separately from the encrypted files. This patch handles the case.

In Windows the value of ENCFS5_CONFIG is always returned in double quotes preventing to use it directly. The quotes must be removed before use. Function readConfig_load() now checks if specified path is quoted and removes the qoutes automatically.