gitcrypt configuration now accepts whitespace separated list of patterns

Pretty much what it says on the tin. When configuring encryption via `gitcrypt init`, you can now give a whitespace-separated list of patterns, which will be echoed to the attributes file, one per line.

```
(...)
Do you want to use .git/info/attributes? [Y/n] n
What files do you want encrypted? [*] /keys/* /credentials/*
kandinski@desire:~/test$ less .gitattributes 
kandinski@desire:~/test$ cat .gitattributes
/keys/* filter=encrypt diff=encrypt
/credentials/* filter=encrypt diff=encrypt
[merge]
    renormalize=true
kandinski@desire:~/test$ 
```