This fixes a bug where attributes of a object would also get added to parent object.

XML to parse
```
<exchange_rate type="XML_RATE_TYPE_EBNK_MIDDLE" valid_from="2011-08-03 00:00:00.0">
    <currency name="AUD" quota="1" rate="18.416"/>
    <currency name="HRK" quota="1" rate="3.25017"/>
    <currency name="DKK" quota="1" rate="3.251"/>
</exchange_rate>
```

BEFORE FIX
```
<CFBasicHash 0xab93140 [0x520b38]>{type = mutable dict, count = 1,
entries =>
	0 : <CFString 0xabacac0 [0x520b38]>{contents = "exchange_rate"} = <CFBasicHash 0xaba99e0 [0x520b38]>{type = mutable dict, count = 6,
entries =>
	0 : <CFString 0xabc1e40 [0x520b38]>{contents = "currency"} = (
        {
        name = AUD;
        quota = 1;
        rate = "18.416";
    },
        {
        name = HRK;
        quota = 1;
        rate = "3.25017";
    },
        {
        name = DKK;
        quota = 1;
        rate = "3.251";
    }
)
	1 : <CFString 0xaba9940 [0x520b38]>{contents = "name"} = <CFString 0xaba9960 [0x520b38]>{contents = "DKK"}
	2 : <CFString 0xaba9990 [0x520b38]>{contents = "rate"} = <CFString 0xaba99c0 [0x520b38]>{contents = "3.251"}
	3 : <CFString 0xaba9980 [0x520b38]>{contents = "quota"} = <CFString 0xaba99a0 [0x520b38]>{contents = "1"}
	4 : <CFString 0xab93180 [0x520b38]>{contents = "type"} = <CFString 0xab931b0 [0x520b38]>{contents = "XML_RATE_TYPE_EBNK_MIDDLE"}
	5 : <CFString 0xab93190 [0x520b38]>{contents = "valid_from"} = <CFString 0xab93220 [0x520b38]>{contents = "2011-08-03 00:00:00.0"}
}

}
```

AFTER FIX
```
<CFBasicHash 0xa689830 [0x520b38]>{type = mutable dict, count = 1,
entries =>
	0 : <CFString 0xa6816a0 [0x520b38]>{contents = "exchange_rate"} = <CFBasicHash 0xa6897c0 [0x520b38]>{type = mutable dict, count = 3,
entries =>
	0 : <CFString 0xa692100 [0x520b38]>{contents = "valid_from"} = <CFString 0xa692190 [0x520b38]>{contents = "2011-08-03 00:00:00.0"}
	1 : <CFString 0xa680860 [0x520b38]>{contents = "currency"} = (
        {
        name = AUD;
        quota = 1;
        rate = "18.416";
    },
        {
        name = HRK;
        quota = 1;
        rate = "3.25017";
    },
        {
        name = DKK;
        quota = 1;
        rate = "3.251";
    }
)
	2 : <CFString 0xa6920f0 [0x520b38]>{contents = "type"} = <CFString 0xa692120 [0x520b38]>{contents = "XML_RATE_TYPE_EBNK_MIDDLE"}
}

}
```
Merge pull request #505 from spenrose/xml-attributes-bug

This fixes a bug where attributes of a object would also get added to parent object.
Add test to make sure that only one timeoutTimer is created.
Move RKRequest timeoutTimer creation to a helper method so that we can test the number of times it is invoked.
Remove duplicate timer creation. Fixes #517.
Fix test for pull request 519
Invalidate the timer before dispatching error delegate callbacks
Fix indentation inconsistencies in dealloc
Added documentation for handling GET and POST params.
Added documentation for RKClient block methods
Remove reference to Specs directory
Implemented support for hydrating to-many relationships. closes #284
Added new pre-flight delegate callbacks for customization of RKRequest and RKObjectLoader instances before dispatch
Set installation path for RestKit.framework to "@executable_path/../Frameworks". closes #543, #544
Remove unnecessary attribute mapping. closes #537
Adding the ability to set a default content decoding other than NSUTF8StringEncoding whenever HTTP headers do not contain any information. closes #547
Merge branch 'development-encoding' into development
Fixed breakage in OS X support
Minor documentation cleanup for paginator
Invalidate timeout timer when POST body data is sent. fixes #535