Remove custom bblfsh build

[ajnavarro]

This is causing the following error on make dependencies after bblfsh sdk update:

11:50 $ make dependencies
cd vendor/gopkg.in/bblfsh/client-go.v3 && make dependencies
make[1]: Entering directory 'work/src/github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/client-go.v3'
go get -v -t -t ./...
github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/client-go.v3/cmd/bblfsh-cli
# github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/client-go.v3/cmd/bblfsh-cli
cmd/bblfsh-cli/main.go:92:30: cannot use ast (type "github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/sdk.v2/uast/nodes".Node) as type "gopkg.in/bblfsh/sdk.v2/uast/nodes".Node in argument to uastyml.Marshal:
	"github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/sdk.v2/uast/nodes".Node does not implement "gopkg.in/bblfsh/sdk.v2/uast/nodes".Node (wrong type for Clone method)
		have Clone() "github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/sdk.v2/uast/nodes".Node
		want Clone() "gopkg.in/bblfsh/sdk.v2/uast/nodes".Node
.ci/Makefile.main:125: recipe for target 'dependencies' failed
make[1]: *** [dependencies] Error 2
make[1]: Leaving directory 'work/src/github.com/src-d/gitbase/vendor/gopkg.in/bblfsh/client-go.v3'
Makefile:21: recipe for target 'bblfsh-client' failed
make: *** [bblfsh-client] Error 2

Signed-off-by: Antonio Jesus Navarro Perez antnavper@gmail.com