update default maven version (3.0.4 -> 3.0.5)
add test cases
changes around setup and setup_locally

* add :mvn_tools_path, :mvn_archive_path and others
* download maven just once and then distribute it to servers
* remove digest checking of downloaded archive.
  if downloaded archive was corrupted, just remote the local cache
  and then retry.
add mvn.exec and mvn.exec_locally
add :mvn_default_options and :mvn_default_options_local
add :mvn_environment to setup environment variables for Maven
setup :default_environment for mvn
add test cases; test_with_remote and test_with_local
add test case; test_with_release_build
0.1.0git
add a variable `:mvn_roles' to setup task roles
use :mvn_target_path and :mvn_target_path_local
use `_merge_environment` to generate environment
create enclosing directory on mvn:update_settings_locally
test :mvn_release_build on remote servers
update develop dependency of capistrano-jdk-installer
JVM args should not join with ":".
update README
release 0.1.0

* setup PATH and JAVA_HOME in :default_environment
* add `mvn.exec()` method to invoke Maven.
* not download archive as many as servers. download just once and then
  distribute it.
* :mvn_update_remotely and :mvn_update_locally are not not exclusive
* add test cases
Merge branch 'release-0.1.0'