dep: fix constraints and update dependencies

Gopkg.toml was emptied out by commit c3e12b5e68 which
seemed to work fine at the time. It turns out that, in
absence of a

  branch = "master"

constraint, dep will use the last tag. We want latest
master, as this is what "go get" fetches, and hence
what Travis uses for testing.

Gopkg.lock

@@ -8,9 +8,10 @@
     "fuse",
     "fuse/nodefs",
     "fuse/pathfs",
+    "internal/utimens",
     "splice"
   ]
-  revision = "a9ddcb8a4b609500fc59c89ccc9ee05f00a5fefd"
+  revision = "291273cb8ce0f139636a6fd7414be3c7e2de6288"
 
 [[projects]]
   branch = "master"
@@ -43,7 +44,7 @@
     "scrypt",
     "ssh/terminal"
   ]
-  revision = "374053ea96cb300f8671b8d3b07edeeb06e203b4"
+  revision = "8ac0e0d97ce45cd83d1d7243c060cb8461dda5e9"
 
 [[projects]]
   branch = "master"
@@ -58,11 +59,11 @@
     "unix",
     "windows"
   ]
-  revision = "01acb38716e021ed1fc03a602bdb5838e1358c5e"
+  revision = "a9e25c09b96b8870693763211309e213c6ef299d"
 
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "87707528925922b2a829b58ba182930ca2a1b0aeef89cca642ecca25259677a2"
+  inputs-digest = "d73a17c7147887cbc6607e2d95e3e4294d3b097a42ebb5ecbcf9b53f8379cb83"
   solver-name = "gps-cdcl"
   solver-version = 1

Gopkg.toml

@@ -1,3 +1,23 @@
+[[constraint]]
+  branch = "master"
+  name = "github.com/hanwen/go-fuse"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/jacobsa/crypto"
+
 [[constraint]]
   name = "github.com/pkg/xattr"
   branch = "master"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/rfjakob/eme"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/crypto"
+
+[[constraint]]
+  branch = "master"
+  name = "golang.org/x/sync"