Merge pull request #56 from tsloughter/profile_deps

rewrite profiles
Merge pull request #61 from tsloughter/master

don't include all */ebin dirs in code path
Ensure dir for plt exists when copying
Merge pull request #65 from fishcakez/plt_copy_lib

Ensure dir for plt exists when copying.
Merge pull request #67 from tsloughter/master

add two cool dudes to the THANKS
Remove profile declarations

No longer needed.
Add support for namespace-based metacommands

And more general namespace support
Dynamic 'do' provider for namespaces

Using a namespace such as 'rebar3 lfe new' will look for the 'new'
command in 'lfe' namespace without the need for a 'do' provider to be
registered in that namespace.

Manually checked that 'rebar3 as <profile> <namespace> command' works,
as well with 'default' and 'do'.

Test suite still needed.
Fix up programmatic interface to rebar3

Now supports arbitrary commands
Tests and fixes for namespaces
Merge pull request #70 from rebar/provider-namespaces

Provider namespaces
update erlydtl provider to use namespaces
set deps back to tsloughter/providers and erlware/relx