Add before/after hooks for `rbenv uninstall`
Support rbenv hook paths that have spaces

Same approach taken in rbenv: sstephenson/rbenv@baf7656d
Fix stubbing programs that have dashes in them
Call `rbenv-*` subcommands directly, not through the `rbenv` executable

Benefits:
- makes it easier to stub `rbenv-*` subcommands in tests
- speeds up subcommands because it skips the main `rbenv` executable

Caveats:
- users are no longer able to call `bin/rbenv-install` or
  `rbenv-uninstall` directly
Add tests for `rbenv install/uninstall` hooks
Merge branch 'hooks'

Closes #368
ruby-build 20131226
Add JRuby 1.7.10
ruby-build 20140110
Remove trailing whitespace from JRuby 1.7.10 definition

Believe it or not, this was causing the following error:

    command not found-build: line 370: build_package_jruby
ruby-build 20140110.1
Run sed without the -E flag.
GNU sed version 4.1.5 on CentOS 5.8 does not support the -E flag:
$ sed -E
sed: invalid option -- E
Merge pull request #491 from marc/master

GNU sed compatibility
Add MAKE_INSTALL_OPTS for packages

Allows for passing environment variables specifically to the "make install"
step of package building.

This can be helpful for providing a different DESTDIR= to a ruby install from
the --prefix that is used
Add tests for RUBY_MAKE_INSTALL_OPTS=
Add mention of RUBY_MAKE_INSTALL_OPTS in README
Add MAKE_INSTALL_OPTS configuration option
Add test for MAKE_INSTALL_OPTS

Also fix the ordering of make install arguments
Fix install file mode for files in share/

install(1) defaults to file mode 0755 which is inappropriate for Ruby
definitions
Test that files in `share/` get installed w/ mode 644