Fixed i18n strings to use a literal textdomain instead of a variable
Add missing text domain. Fixes #121
Strict Error in TGM_Bulk_Installer_Skin class on update to WP3.6

TGM_Bulk_Installer_Skin::before() should be compatible with WP_Upgrader_Skin::before()
TGM_Bulk_Installer_Skin::after() should be compatible with WP_Upgrader_Skin::after()

added in default variable to methods
Merge pull request #123 from hugosaner/develop

Strict Error in TGM_Bulk_Installer_Skin class on update to WP3.6, fixes #122
Remove __()

It is not need as it the php does not need to be translated
TGM_Plugin_Activation::$menu is always replaced by current ?page=xxx parameter's value due to 

TGM_Plugin_Activation::$menu is always replaced by current ?page=xxx parameter's value due to = (assignment) operator used instead of == or ===. This made install_plugin_page() to be active in all plugin / theme options pages.
Merge pull request #128 from grappler/patch-1

Remove redundant __() since the string has already been internationalized already.
Merge pull request #129 from asadkn/patch-1

Only load the Install classes on the Install page.
Remove sanitize_key calls on string literals
Merge pull request #144 from mpeshev/mpfix

Remove sanitize_key calls on string literals
Removed translation of a variable
Merge pull request #153 from hugosaner/patch-1

Removed translation of a variable
Lots of changes to start 2.4.0 beta. More to come with official release!
Merging branches.