Log Message:
Update ruby-highline to 1.7.7.

### 1.7.7 / 2015-09-22
* Make HighLine::Question coerce its question argument into a String. \ 
(@97-109-107 and Abinoam P. Marques Jr. (@abinoam), #159, PR #160)

### 1.7.6 / 2015-09-17
* Fix a typo in a var name affecting solaris. (Danek Duvall (@dhduvall) and \ 
Abinoam P. Marques Jr. (@abinoam), #155, PR #156)

### 1.7.5 / 2015-09-14
* Support jruby9k for system extensions (Michael (@mmmries), PR #153)

### 1.7.4 / 2015-06-16
* Workaround on #55 for stty