fix bug: src config could be string or array, and update readme

[lovetingyuan]

if the src config is a string type, then will throw an error: { Error: EISDIR: illegal operation on a directory, read errno: -4068, code: 'EISDIR', syscall: 'read' }, and the src type in readme is also wrong

[coveralls]

Coverage decreased (-0.5%) to 98.413% when pulling 9294dee on lovetingyuan:master into c8c702f on selaux:master.

[coveralls]

Coverage decreased (-0.5%) to 98.413% when pulling 9294dee on lovetingyuan:master into c8c702f on selaux:master.

[coveralls]

Coverage decreased (-0.5%) to 98.413% when pulling 9294dee on lovetingyuan:master into c8c702f on selaux:master.

[coveralls]

Coverage decreased (-0.5%) to 98.413% when pulling 9294dee on lovetingyuan:master into c8c702f on selaux:master.