Implement connection string

[shaan1337]

Fixes #41

Note: This PR has been opened against use-https-option branch so that it's retargeted to master after the former is merged.

Examples:

single node:
EventStoreClientSettings.Create("esdb://localhost"); //with hostname only
EventStoreClientSettings.Create("esdb://localhost:2113"); //with hostname and port
EventStoreClientSettings.Create("esdb://user:pass@localhost:2113"); //with username and password
EventStoreClientSettings.Create("esdb://user:pass@localhost:2113/"); //extra forward slash also works
EventStoreClientSettings.Create("esdb://user:pass@localhost:2113?tlsVerifyCert=false"); //disables server certificate validation
EventStoreClientSettings.Create("esdb://user:pass@localhost:2113?tls=false"); //connects over http instead of https

cluster:
EventStoreClientSettings.Create("esdb://host1,host2,host3"); //with hostnames only
EventStoreClientSettings.Create("esdb://host1:1234,host2:4321,host3:3231"); //with hostnames and port
EventStoreClientSettings.Create("esdb://user:pass@host1:1234,host2:4321,host3:3231?nodePreference=follower"); //with username and password
EventStoreClientSettings.Create("esdb://host1,host2,host3?tls=false"); //connects over http instead of https
EventStoreClientSettings.Create("esdb://host1,host2,host3?tlsVerifyCert=false"); //disables server certificate validation

All parameters:

ConnectionName / string
MaxDiscoverAttempts / int
DiscoveryInterval / int (milliseconds)
GossipTimeout / int (milliseconds)
NodePreference / string
Tls / bool
TlsVerifyCert / bool
OperationTimeout / int (milliseconds)
ThrowOnAppendFailure / bool

changes have been made as requested

[pgermishuys]

Let's try and marry up the units to that of the server.

[hayley-jean]

Just two things I've found during testing:

1. It's possible to provide duplicate values in the connection string. This results in the last one specified taking effect, should we leave this or should this cause an error?
2. Perhaps there should be some validation checking for the ? after specifying the host? There's no error if the ? is omitted, but the settings don't take effect.

[shaan1337]

@hayley-jean good catch, thanks for the feedback, I've addressed these issues in these 2 commits:
f4ffa9c
bfad201

[pgermishuys]

Hey @shaan1337, good work on this!
Is there any particular reason why we are requiring a / and ? after the hosts to indicate extra parameters? Wouldn't a single character such as a ; give it a better user experience?

[shaan1337]

@pgermishuys yes, the connection string mimics a URL as much as possible and ? is part of the syntax: https://en.wikipedia.org/wiki/URL#Syntax

Right now we enforce a ? just after the / but the path could later on point to a specific resource, e.g if we later on support multi-tenancy we could specify the database name in the path:
EventStoreClientSettings.Create("esdb://localhost/mydatabase1?tls=false");

[shaan1337]

@pgermishuys @hayley-jean @thefringeninja
I've added a new commit (52ffeab) to make the path optional and removed the last 2 commits. It's up for review again (except that some unrelated flaky test is failing intermittently: EventStore.Client.listing_users.returns_all_users)