add travis

.travis.yml

+language: go
+
+go:
+  - 1.5.1
+
+services:
+  - redis-server
+  - mysql
+  - postgresql
+  - memcached
+env:
+  - ORM_DRIVER=sqlite
+  - ORM_DRIVER=mysql
+  - ORM_DRIVER=postgres
+before_script:
+  - sh -c "if [ '$DB' = 'postgres' ]; then export ORM_SOURCE='user=postgres dbname=orm_test sslmode=disable'; psql -c 'create database orm_test;' -U postgres; fi"
+  - sh -c "if [ '$DB' = 'mysql' ]; then export ORM_SOURCE='root:@/orm_test?charset=utf8'; mysql -u root -e 'create database orm_test;'; fi"
+  - sh -c "if [ '$DB' = 'sqlite' ]; then export ORM_SOURCE=$TRAVIS_BUILD_DIR/orm_test.db; touch $TRAVIS_BUILD_DIR/orm_test.db; fi"