feat(build runner): added in context, dockerfile_location

this is a new feature meant to allow people to use any file as
  a dockerfile and any folder as a context directory

data/migrations/versions/a6c463dfb9fe_back_fill_build_expand_config.py

@@ -0,0 +1,85 @@
+"""back fill build expand_config
+
+Revision ID: a6c463dfb9fe
+Revises: e2894a3a3c19
+Create Date: 2017-03-17 10:00:19.739858
+
+"""
+
+# revision identifiers, used by Alembic.
+import json
+import os
+
+from data.database import RepositoryBuildTrigger
+
+revision = 'a6c463dfb9fe'
+down_revision = 'e2894a3a3c19'
+
+from alembic import op
+
+
+def upgrade(tables):
+  repostioryBuildTriggers = RepositoryBuildTrigger.select()
+  for repositoryBuildTrigger in repostioryBuildTriggers:
+    config = json.loads(repositoryBuildTrigger.config)
+    repositoryBuildTrigger.config = json.dumps(get_config_expand(config))
+
+
+def downgrade(tables):
+  repostioryBuildTriggers = RepositoryBuildTrigger.select()
+  for repositoryBuildTrigger in repostioryBuildTriggers:
+    config = json.loads(repositoryBuildTrigger.config)
+    repositoryBuildTrigger.config = json.dumps(get_config_expand(config))
+
+
+def create_context(current_subdir):
+  if current_subdir == "":
+    current_subdir = os.path.sep + current_subdir
+
+  if current_subdir[len(current_subdir) - 1] != os.path.sep:
+    current_subdir += os.path.sep
+
+  context, _ = os.path.split(current_subdir)
+  return context
+
+
+def create_dockerfile_path(current_subdir):
+  if current_subdir == "":
+    current_subdir = os.path.sep + current_subdir
+
+  if current_subdir[len(current_subdir) - 1] != os.path.sep:
+    current_subdir += os.path.sep
+
+  return current_subdir + "Dockerfile"
+
+
+def get_config_expand(config):
+  """ A function to transform old records into new records """
+  if not config:
+    return config
+
+  # skip records that have been updated
+  if "context" in config or "dockerfile_path" in config:
+    return config
+
+  config_expand = {}
+  if "subdir" in config:
+    config_expand = dict(config)
+    config_expand["context"] = create_context(config["subdir"])
+    config_expand["dockerfile_path"] = create_dockerfile_path(config["subdir"])
+
+  return config_expand
+
+
+def get_config_contract(config):
+  """ A function to delete context and dockerfile_path from config """
+  if not config:
+    return config
+
+  if "context" in config:
+    del config["context"]
+
+  if "dockerfile_path" in config:
+    del config["dockerfile_path"]
+
+  return config