Fixed constant Xcode crash on startup.

The problem is rvm. If I "whereis pod" there is nothing. Another thing is that in ```- (void)cocoaPodsVersion:(KFCocoaPodsVersionBlock)versionBlock``` serialized yaml looks like this:
```
<__NSArrayM 0x600000053260>(
.bashrc
)
```

And then, without any checks we are trying to get version ```NSString *version = yaml[0][@"version"];```, but ```yaml[0] ``` is type of NSString and not NSDictionary.