Add Stackless 2.7.7, Stackless 2.7.8, and Stackless 3.4.1 (fixes #252)

plugins/python-build/share/python-build/stackless-2.7.7

@@ -0,0 +1,3 @@
+require_cc
+install_package "readline-6.3" "http://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
+install_package "stackless-dev-stackless-a182f63395c3" "https://bitbucket.org/stackless-dev/stackless/get/v2.7.7-slp.tar.bz2#88ca1169d878fd860f6d04d9e509399f2bc25ec0b692fd5998640c5d0d489c85" ldflags_dirs standard verify_py27 ensurepip

plugins/python-build/share/python-build/stackless-2.7.8

@@ -0,0 +1,3 @@
+require_cc
+install_package "readline-6.3" "http://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
+install_package "stackless-dev-stackless-ff29dd4f67de" "https://bitbucket.org/stackless-dev/stackless/get/v2.7.8-slp.tar.bz2#4d61c630c9a6c445b03c3b1a7d2391d5014a89d55b6d9d94be561fea34f158dc" ldflags_dirs standard verify_py27 ensurepip

plugins/python-build/share/python-build/stackless-3.4.1

@@ -0,0 +1,3 @@
+require_cc
+install_package "readline-6.3" "http://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
+install_package "stackless-dev-stackless-983d1323d146" "https://bitbucket.org/stackless-dev/stackless/get/v3.4.1-slp.tar.bz2#cae24c9d1d9b9ffd27d3ed0d9baae980df4a55fb27c497ef939709a3950ba538" ldflags_dirs standard verify_py34 ensurepip