Make taskdefs play nicer when included in parent build file

Change-Id: I6d650d700aa0bf6324fc877fe16970674dd07c0c
Reviewed-on: http://gerrit.dmdirc.com/2019
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>

Change-Id: I9a59a3866f553757fbce5739e04b1de2a24da192
Reviewed-on: http://gerrit.dmdirc.com/2018
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>

Change-Id: I2c9293b39bee7a604191ae22349cad48c740af78
Fixes-issue: CLIENT-139
Reviewed-on: http://gerrit.dmdirc.com/2015
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager

Change-Id: I7d5a1d15689723fe21d0dfded6a76e2d80025e23
Reviewed-on: http://gerrit.dmdirc.com/1657
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Greg Holmes <greg@dmdirc.com>