Run patch_neutron function from the correct dir

The patch_neutron function is used in a few places and makes some
assumptions about the current working directory. These assumptions are
breaking other uses of patch_neutron (namely, Jenkins packaging job).
This patch removes the "cd" in the function and moves it into
20-akanda.sh, thus addressing pathing without having to modify anything
else (namely, Jenkins packaging jobs).
Looks like everything checks out:

```
+ echo_summary 'Patching Neutron'
++ [[ -t 3 ]]
++ [[ True != \T\r\u\e ]]
++ echo -e Patching Neutron
++ patch_neutron
2014-12-18 20:39:20.241 | Patching Neutron
++ cd /opt/stack/neutron
+++ git diff 'HEAD^'
+++ awk '{ print $1 }'
+++ md5sum
++ LAST_COMMIT_HASH=7421d2cdd52b7bf47db0423011e6ac18
+++ cat /home/vagrant/devstack/patches/remove_lazy_join_from_ipallocationpools.patch
+++ awk '{ print $1 }'
+++ md5sum
++ PATCH_HASH=3fc92731f45fca3529bc8159e193c598
++ '[' 7421d2cdd52b7bf47db0423011e6ac18 '!=' 3fc92731f45fca3529bc8159e193c598 ']'
++ git fetch https://review.openstack.org/openstack/neutron refs/changes/48/17248/4
remote: Counting objects: 36, done
remote: Finding sources: 100% (19/19)
remote: Total 19 (delta 1), reused 3 (delta 1)
Unpacking objects: 100% (19/19), done.
From https://review.openstack.org/openstack/neutron
 * branch            refs/changes/48/17248/4 -> FETCH_HEAD
++ git cherry-pick FETCH_HEAD
error: could not apply ae6e7e5... add routerport instead of overloading device_id
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
++ true
++ git add .
++ git commit -m 'DreamHost: Add routerport instead of overloading device_id(merged with conflicts)'
[stable/icehouse 948cd2f] DreamHost: Add routerport instead of overloading device_id(merged with conflicts)
 Author: Mark McClain <mark.mcclain@dreamhost.com>
 Committer: vagrant <vagrant@devstack-develop>
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    git commit --amend --reset-author

 9 files changed, 2445 insertions(+), 301 deletions(-)
 create mode 100644 neutron/plugins/nicira/NeutronPlugin.py
++ git apply /home/vagrant/devstack/patches/add_routerport_instead_of_overloading_device_id.patch
++ git add .
++ git commit -m 'DreamHost: Fix conflicts introduced by previous patch'
[stable/icehouse fc4da56] DreamHost: Fix conflicts introduced by previous patch
 Committer: vagrant <vagrant@devstack-develop>
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    git config --global user.name "Your Name"
    git config --global user.email you@example.com

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    git commit --amend --reset-author

 2 files changed, 9 deletions(-)
++ git apply /home/vagrant/devstack/patches/restore_icehouse_api.patch
++ git add .
++ git commit -m 'DreamHost: Restore icehouse api'
[stable/icehouse e28a44d] DreamHost: Restore icehouse api
 Committer: vagrant <vagrant@devstack-develop>
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fter doing this, you may fix the identity used for this commit with:

    git commit --amend --reset-author

 1 file changed, 4 insertions(+), 3 deletions(-)
++ git apply /home/vagrant/devstack/patches/fix_neutron_to_nova_notification.patch
++ git add .
++ git commit -m 'DreamHost: Fix neutron-to-nova notification about ports creation'
[stable/icehouse 7debccb] DreamHost: Fix neutron-to-nova notification about ports creation
 Committer: vagrant <vagrant@devstack-develop>
Your name and email address were configured automatically based
on your username and hostname. Please check that they are accurate.
You can suppress this message by setting them explicitly:

    git config --global user.name "Your Name"
    git config --global user.email you@example.com

After doing this, you may fix the identity used for this commit with:

    git commit --amend --reset-author

 1 file changed, 2 insertions(+), 1 deletion(-)
++ git apply /home/vagrant/devstack/patches/remove_lazy_join_from_ipallocationpools.patch
++ git add .
++ git commit -m 'DreamHost: Remove lazy join from ipallocationpools'
[stable/icehouse 1c85e70] DreamHost: Remove lazy join from ipallocationpools
 Committer: vagrant <vagrant@devstack-develop>
Your name and email address were configured automatically based
on your username and hostname. Please check that they are accurate.
You can suppress this message by setting them explicitly:

    git config --global user.name "Your Name"
    git config --global user.email you@example.com

After doing this, you may fix the identity used for this commit with:

    git commit --amend --reset-author

 1 file changed, 1 deletion(-)
++ echo_summary 'Installing Akanda'
++ [[ -t 3 ]]
++ [[ True != \T\r\u\e ]]
++ echo -e Installing Akanda
++ configure_akanda
2014-12-18 20:39:24.868 | Installing Akanda
```