added assert_map_results to map.rb which provides a uniform way of asserting Calabash::Cucumber::Map.map calls were successful

## motivation

```
calabash-ios-example - LPSimpleExample-cal

any ruby version
$ be calabash-ios version => 0.9.166.pre3
server_version['version'] => "0.9.163"
any iOS version
simulator or device
start_test_server_in_background
# go to the tab with the table view

touch("view marked:'Third'")
[
[0] {
"label" => "Third",
"class" => "UITabBarButton"
}
]
# look for a Cell 12 - it is not visible which is expected
irb(main):005:0> query("tableViewCell descendant marked:'Cell 12'")
[]

# show that scroll to row with mark works
irb(main):006:0> scroll_to_row_with_mark('Cell 12')
[
[0] "<UITableView: 0xa2f0a00; frame = (0 0; 320 568); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x9b9db50>; layer = <CALayer: 0x9b9adc0>; contentOffset: {0, 0}>"
]

# try looking for a mark that does not exist
irb(main):007:0> scroll_to_row_with_mark('mark does not exist')
[
[0] nil
]

# expected - an exception because the mark is not found
# found - an array [ nil ]

regression: since at least 0.9.162

```

## Notes

* bumped version to 0.9.166pre4
* added documentation to some methods


## Testing

* [briar 0.1.3.b10](https://github.com/jmoody/briar/tree/0.1.3.b10)
* [briar-ios-example 1.1.6](https://github.com/jmoody/briar-ios-example/tree/1.1.6-expecting-map-results)

### Briar

* tags 
    - @trello_631 
* ruby versions
   - [x] ruby 2.0
   - [x] ruby 1.9
   - [x] ruby 1.8 
    
#### `NO_LAUNCH=1` ==> Manually Launching ==> UIA _not_ available

- [x] iPhone 4S iOS 6
- [x] iPad 1 iOS 5.1.1 
- [x] iPhone Simulator iOS 6.1
- [x] iPad Simulator iOS 6.1

####  `NO_LAUNCH=0` ==> Launching with Instruments ==> UIA available

- [x] iPhone 4S iOS 6 
- [x] iPhone 5C iOS 7.0.2
- [x] iPad 4 iOS 7.0.3
- [x] iPhone Simulator iOS 7
- [x] iPad Simulator iOS 7

#### `NO_LAUNCH=0` ==> Launching with Sim Launcher ==> UIA _not_ available

- [x] iPhone Simulator iOS 6.1
- [x] iPad Simulator iOS 6.1

### XTC

### LPSimpleExample (smoke test)
[LPSimpleExample](https://github.com/jmoody/calabash-ios-example)

https://testcloud.xamarin.com/s/HGaESdCLUbUx_Q

- [x] Apple iPad 2 (5.1.1) 
- [x] Apple iPad Air (7.0.4)
- [x] Apple iPhone 4S (5.1.1)
- [x] Apple iPhone 4S (7.0.4)
- [x] Apple iPhone 4S (6.1.3)
- [x] Apple iPhone 3GS (6.1.3)
- [x] Apple iPad 2 (6.1.3)
- [x] Apple iPad 4th Gen (7.0.4)
- [x] Apple iPhone 5 (6.1.4)
- [x] Apple iPhone 5 (7.0.4)
- [x] Apple iPhone 5C (7.0.4) 
- [x] Apple iPhone 5S (7.0.4)
- [x] Apple iPod touch 5th Gen (7.0.4)
- [x] Apple iPod touch 5th Gen (6.1.3)

#### ruby versions

- [x] ruby 2.0
- [x] ruby 1.9
- [x] ruby 1.8 - had to specify gem 'mime-types', '1.25'

### Briar iOS Example @trello_631

https://testcloud.xamarin.com/s/VffdxlQr1pNElA

- [x] Apple iPad 2 (5.1.1) 
- [x] Apple iPad Air (7.0.4)
- [x] Apple iPhone 4S (5.1.1)
- [x] Apple iPhone 4S (7.0.4)
- [x] Apple iPhone 4S (6.1.3)
- [x] Apple iPhone 3GS (6.1.3)
- [x] Apple iPad 2 (6.1.3)
- [x] Apple iPad 4th Gen (7.0.4)
- [x] Apple iPhone 5 (6.1.4)
- [x] Apple iPhone 5 (7.0.4)
- [x] Apple iPhone 5C (7.0.4) 
- [x] Apple iPhone 5S (7.0.4)
- [x] Apple iPod touch 5th Gen (7.0.4)
- [x] Apple iPod touch 5th Gen (6.1.3)