[Build] Test build OpenTK with mono 3.2.6 and 2.10.11

Squashed commit of the following:

commit 15ec03cd3f5f09ed88c51b62393fd6fa3476b03a
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 15:53:18 2014 +0100

    [Build] Fixed missing '' typo

commit 9e3dcad6124db52ec9035a8e6126244d9c856bfd
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 15:27:07 2014 +0100

    [Build] Install mono either from pwd or from mounted /Volume

commit b7303b68eaf3f4867e73a89fd22bd11caecf4f38
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 15:21:40 2014 +0100

    [Build] Do not stop build when wget fails

    The build stops iff no valid mono framework can be installed

commit 875c23294e6adc5061589576c6eabd43894ae9dd
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 15:13:08 2014 +0100

    [Build] Fix 3.2.x and 2.10.x mono download urls

commit 7bcbc789ce89cd16e06d5a62b05dd249432fcba0
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 11:58:57 2014 +0100

    [Build] Use .pkg file for mono installation on Travis

commit 60fef5aa7db9929c99ef22a778c87f634bcba266
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 11:43:12 2014 +0100

    [Build] Detect *.yml as text files

commit 7fb42856f187cb0503494523d2e524df8bda1cbc
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 11:40:07 2014 +0100

    [Build] Move first xbuild run to pre-build scripts

commit e1cfcf76202ba82d196cc6dceabb25c93c24ef87
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 11:38:19 2014 +0100

    [Build] Fixed mono 3.2.6 download url

commit c6941844353b53a7e8fb614565243ffbc31679d7
Author: thefiddler <stapostol@gmail.com>
Date:   Mon Feb 24 11:32:16 2014 +0100

    [Build] Run xbuild twice for GlobalAssemblyInfo.cs

    This works around an issue in xbuild, where pre-build events
    are not resolved correctly. The first run generates
    GlobalAssemblyInfo.cs; the second run actually builds the project