Sometimes the image is not found and for those artist/albums there is no
way for pointing the image path to default image path so some helper
functions have been added so that we can point them to default Image.
Following Functions have been added :
1. SetCacheDir : Sets the Cache Directory
2. CHANGE AddToCache the image path is now the Cache Directory +
image Path
The Following New Functions have been added
1. AddToCache Adds to the CACHE_LIST map
2. GetFromCache Retrieves path from CACHE_LIST map
3. Rename WriteToCache -> WriteCache()
4. GenerateName now replaces spaces with underscores.
The Caching Module Caches the images that have been extracted and for
persistence writes the images to a cache file.
In the cache file the data is stored by tab separated values
`%s\t%s\t%s`
the cache is first loaded in the memory ( CACHE_LIST ) during the start of application
and then extracted images are added to the map CACHE_LIST which is
writtern to the cache file before exiting the program.
