Use strict comparisons when matching scrub keys

[ghostal]

Better solution for bug highlighted in PR #64.

Because of the loose comparison used by default by in_array(), the code below causes the output that follows:

$fruits = ['apple', 'banana', 'cherry'];
var_dump(in_array(0, $fruits));
var_dump(in_array(0, $fruits, true));

bool(true)
bool(false)

In the rollbar library, this means that any zero indexed array always has its first element scrubbed.

[brianr]

This is great, thanks @ghostal!

I've verified that the new test fails on the old code, and passes after the fix.

Will get a new release out shortly.