Added new script command
Added script cmd in cmd.go
Add switchContext function to context.go
Added panicked attribute to context.go

This attribute is set to false during initalisation, and it's set to
true when error arises.
Go-shellwords added to Gomfile

This packages allows us to parse shell commands. Useful for
script_run.go (later added)
Refactored main.go

The main function - whuch runs aptly commands - has been taken out from
main.go and included to the cmd package. This is useful for the aptly
script run command, which should use that behaviour.
aptly script run implementation

This new aptly command will allow to run multiple commands within a single
aptly command, running in a single thread. The commands can be included
in a text file or added to the aptly script run command in one line,
separated by comas ','.
If one command returns an error, then all the subsequent commands will
be skipped.
Each command output will appear on the console within coloured strings,
clearly stating which command is running and the start and the end of
the received output.
Aptly script has now become aptly task

It makes more sense. Multiple lines of aptly commands can now be called
'aptly tasks' which could potentially be automated, in the future?
Better wording for task run message.
Fixed t03_help:MainTest failing due to new cmd
Making sure context is initialised before using it

Now checkong context is not nil before setting panicked = true
Added RunTask acceptance tests

Added a basic RunTask test to test the functionality of the new aptly
task run command. More to come...
Adding filename flag to specify task run filename.

Just realised commands can not have any subcommands and therefore
consist of single words (for example serve or version). Hence I can't
assume that if len(args)==1 then the user has entered the filename.
I have created the filename flag so the user is forced to specify it
when they wish to run aptly tasks from files.
Fixed a bug with the context switching

The context switching wasn't really happening. Now the issue is fixed.
Merge branch 'script_run_command' of https://github.com/queeno/aptly into queeno-script_run_command
Use go1.3.1.
Refactoring: remove context switching, another way to catch panics, colored output. #96
Merge branch 'queeno-script_run_command'