show --modules will output one module per line

As suggested by @agladysh in #210

So the output of, say, `luarocks show --modules oauth` will be:

~~~~
OAuth.helpers
OAuth
OAuth.coreLuaNode
OAuth.coreLuaSocket
~~~~

instead of 

~~~~
OAuth.helpers OAuth OAuth.coreLuaNode OAuth.coreLuaSocket
~~~~
Fix documentation. Thanks @ignacio!
Use \n as separator to keys_as_string
Merge pull request #223 from ignacio/patch-2

show --modules will output one module per line
Why was this here? :)
mention --verbose option in help
unquoted path fails when spaces are in the filename
adds a --branch=<branchname> option. The branchename is passed as BRANCH to the rockspec environment
updated the `--branch` option to work through updating the rockspec `source.branch` field
Additionally a fix for the `git` module, to use command quoting
Merge pull request #225 from Tieske/md5_fix

unquoted path fails when spaces are in the filename
Merge pull request #224 from Tieske/help_update

mention --verbose option in help
added help info to build and make commands
Merge pull request #226 from Tieske/branch_option

add --branch=<branchname> option
remove rocksserver settings from windows installer
Merge pull request #227 from Tieske/install_fix

remove rocksserver settings from windows installer
Fix logic to report errors when loading config.lua. Closes #228. Please reopen if problem persists.
Merge branch 'master' of github.com:keplerproject/luarocks
Add more tests.
remove dead local variable wrap_bin_scripts

now, the job is done by a call to repos.should_wrap_bin_scripts()
Merge pull request #230 from fperrad/patch-1

remove dead local variable wrap_bin_scripts