add license into all .gem files

Author: mattn

mruby-alarm.gem

@@ -4,3 +4,4 @@ author: k0u5uk3
 website: https://github.com/k0u5uk3/mruby-alarm
 protocol: git
 repository: https://github.com/k0u5uk3/mruby-alarm.git
+license: MIT

mruby-allegro.gem

@@ -4,3 +4,4 @@ author: cremno
 website: https://github.com/cremno/mruby-allegro
 protocol: git
 repository: https://github.com/cremno/mruby-allegro.git
+license: MIT

mruby-allocate.gem

@@ -4,3 +4,4 @@ author: ppibburr
 website: https://github.com/ppibburr/mruby-allocate
 protocol: git
 repository: https://github.com/ppibburr/mruby-allocate.git
+license: MIT

mruby-ansi-colors.gem

@@ -3,4 +3,5 @@ description: Extends String class to use ANSI color escape codes.
 author: Mav7
 website: https://github.com/Mav7/mruby-ansi-colors
 protocol: git
-repository: https://github.com/Mav7/mruby-ansi-colors.git
+repository: https://github.com/Mav7/mruby-ansi-colors.git
+license: GPL-2.0

mruby-apr.gem

@@ -4,3 +4,4 @@ author: Jared Breeden
 website: https://github.com/jbreeden/mruby-apr
 protocol: git
 repository: https://github.com/jbreeden/mruby-apr.git
+license: Apache Version 2

mruby-arduino.gem

@@ -3,4 +3,5 @@ description: Arduino binding
 author: kyab
 website: https://github.com/kyab/mruby-arduino
 protocol: git
-repository: https://github.com/kyab/mruby-arduino.git
+repository: https://github.com/kyab/mruby-arduino.git
+license: MIT

mruby-argon2.gem

@@ -7,3 +7,4 @@ repository: https://github.com/Asmod4n/mruby-argon2.git
 dependencies:
 - mruby-errno
 - mruby-sysrandom
+license: Apache-2.0

mruby-argtable.gem

@@ -4,3 +4,4 @@ author: ["Uchio Kondo", "Stewart Heitmann"]
 website: https://github.com/udzura/mruby-argtable
 protocol: git
 repository: https://github.com/udzura/mruby-argtable.git
+license: BSD

mruby-at_exit.gem

@@ -4,3 +4,4 @@ author: ksss
 website: https://github.com/ksss/mruby-at_exit
 protocol: git
 repository: https://github.com/ksss/mruby-at_exit.git
+license: MIT

mruby-audite.gem

@@ -4,3 +4,4 @@ author: Matthias Georgi
 website: https://github.com/georgi/mruby-audite
 protocol: git
 repository: https://github.com/georgi/mruby-audite.git 
+license: MIT