Move dependency handing earlier

New developers, such as myself, will find that go build doesn't really
work out of the box. The needed godeps steps is documented but it is
mentioned later in the README file. Inpatient developers may not read
everything top-to-bottom to see this patch moves the relevant section
into the correct spot.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>

README.md

@@ -48,6 +48,20 @@ At this point you will have the git local repository of the `snappy` source at
 `$GOPATH/github.com/ubuntu-core/snappy/snappy`. The source for any
 dependent packages will also be available inside `$GOPATH`.
 
+### Dependencies handling
+
+To generate dependencies.tsv you need `godeps`, so
+
+    go get launchpad.net/godeps
+
+To obtain the correct dependencies for the project, run:
+
+    godeps -t -u dependencies.tsv
+
+If the dependencies need updating
+
+    godeps -t ./... > dependencies.tsv
+
 ### Building
 
 To build, once the sources are available and `GOPATH` is set, you can just run
@@ -99,19 +113,6 @@ If a test hangs, you can enable verbose mode:
 (or -check.v for less verbose output).
 
 There is more to read about the testing framework on the [website](https://labix.org/gocheck)
-### Dependencies handling
-
-To generate dependencies.tsv you need `godeps`, so
-
-    go get launchpad.net/godeps
-
-To obtain the correct dependencies for the project, run:
-
-    godeps -t -u dependencies.tsv
-
-If the dependencies need updating
-
-    godeps -t ./... > dependencies.tsv
 
 
 [travis-image]: https://travis-ci.org/ubuntu-core/snappy.svg?branch=master