add dependence database

.travis.yml

@@ -12,6 +12,10 @@ env:
   - ORM_DRIVER=sqlite   ORM_SOURCE=$TRAVIS_BUILD_DIR/orm_test.db
   - ORM_DRIVER=mysql    ORM_SOURCE="root:@/orm_test?charset=utf8"
   - ORM_DRIVER=postgres ORM_SOURCE="user=postgres dbname=orm_test sslmode=disable"
+install:
+  - go get github.com/lib/pq
+  - go get github.com/go-sql-driver/mysql
+  - go get github.com/mattn/go-sqlite3
 before_script:
   - sh -c "if [ '$ORM_DRIVER' = 'postgres' ]; then psql -c 'create database orm_test;' -U postgres; fi"
   - sh -c "if [ '$ORM_DRIVER' = 'mysql' ]; then mysql -u root -e 'create database orm_test;'; fi"