Fix erroneous SSL certificate warnings

If you attempted to use SSL to connect to a server that speaks
STARTTLS, you should get an SSL protocol error.  Instead, you
were likely to get an "Unrecognized Certificate" error that shows
you an unrelated certificate chain and asks you to accept it or
reject it.  Neither action would work because the actual problem
had nothing to do with certificates.  The unrelated certificate
chain that popped up had been statically stored when validating
a prior connection to a different server.

With this patch, certificate chains are no longer stored statically
when validating server connections.

Issue 5886 is an example of a user experiencing this problem.
Update strings.xml

New strings added
Merge pull request #366 from bboa/patch-1

Update strings.xml
Load unread and flagged message counts lazily in the folder list

The new method is a little bit janky, but a little bit of jank is better than 2n
heavy SQL count queries per folder before we even show the folder list.

On my 200 folder account, display of the folder list activity drops from 10+s to
< 1s
SK translation
Merge pull request #369 from pylerSM/patch-1

Updates to Slovakian translation
Some kernels have frandom and erandom

When a users kernel has frandom and erandom this would cause the whole app to crash.

When using erandom the system doesn't use any entropy at all.
add notes about the reason for https://github.com/k9mail/k-9/pull/367
Merge pull request #365 from zjw/Issue_5886_misleading_ssl_errors

Fix erroneous SSL certificate warnings
Fix flagging of messages in message list
4.510 changelog
Bumped manifest to 4.510
Clean-up related to certificate chains

Per comments in pull request #365