fix panic in Writer

Commit 766cfec introduced this bug by defining an incorrect split
function. First it breaks the old behavior because it never splits at
newlines now. Second, it causes a panic because it never tells the
scanner to stop. See the bufio.ScanLines function, something like:
```
if atEOF && len(data) == 0 {
	return 0, nil, nil
}
```
is needed to do that.

This commit fixes it by restoring the old behavior and calling
bufio.ScanLines but also keep the 64KB check in place to avoid buffering
for to long.

Two tests are added to ensure it is working as expected.

Fixes sirupsen#1383

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Revert "Merge pull request sirupsen#1376 from ozfive/master"

This reverts commit 6acd903, reversing
changes made to e59b167.

Merge pull request sirupsen#1339 from xieyuschen/patch-1

Use text when shows the logrus output

Merge pull request sirupsen#1339 from xieyuschen/patch-1

Use text when shows the logrus output

Merge pull request sirupsen#1362 from FrancoisWagner/fix-data-race-in…

…-hooks-test-pkg

Fix data race in hooks.test package

Merge pull request sirupsen#1343 from sirupsen/dbd-upd-dep

update dependencies

Merge pull request sirupsen#1244 from sirupsen/dbd-release

update changelog

Merge pull request sirupsen#1231 from sirupsen/dbd-cleanup

cleanup

Merge pull request sirupsen#1230 from sirupsen/new-release

update changelog

Merge pull request sirupsen#1145 from sirupsen/custom_buffer_pool

Add an API to plug a custom buffer free item mangement system