Trailing space as + causes a string param to not be decoded

Example
```
ToCountry=US&Body=No%2C+I%E2%80%99m+ill+&FromCountry=US
```
Notice the + sign at the end of the Body param

After calling `.parse` the Body param is not decoded
```
{"ToCountry":"US","Body":"No%2C I%E2%80%99m ill ","FromCountry":"US"}
```

It works if the trailing + sign is at the end of the string
```
ToCountry=US&FromCountry=US&Body=No%2C+I%E2%80%99m+ill+
```
Once parsed
```
{"ToCountry":"US","FromCountry":"US","Body":"No, I’m ill "}
```