Update Mono.Security.dll assembly to Mono version 3.4.0

Fix #264
Make Npgsql use SSLStream for ssl connections instead of using Mono.Security.

Mono.Security assembly is used by Npgsql to provide ssl support.
SSLStream class found in .Net class library also provides support for ssl.
Before this patch, Npgsql used Mono.Security by default.
With this change, it will use SSLStream class found in .Net class library.
Add tests for float4 and float8 NaN inserting.
Fix #217 when handling NaN for float4 and float8 datatypes.

After commit 854862aeb4ba2c7f6d6cd321baeddbddbeca74fd Npgsql wasn't
adding quotes around float4 and float8 values.

But according to documentation, NaN values need to be quoted.

Separated handling of float4 and float8 conversion routines.
Add support to handle NaN values inside arrays. Thanks @glenebob for heads up.

Add tests for Float array.
Fix bug #280. A DbElementExpression can have a Limit(Sort(Project(...))) as child expression. Then the column in the projection must be projected all the way up.
Clarified a comment in the code
Merge pull request #281 from Emill/remove-unnecessary-aliases

Fix bug #280. A DbElementExpression can have a Limit(Sort(Project(...)))...
EF: Implement an operator table with precedences, instead of adding parentheses in an ad-hoc way thas sometimes generates wrong SQL.
Merge branch 'master' of https://github.com/npgsql/Npgsql into operator-precedence-ef
Implement the DateDiff functions. The old implementation wasn't even close to do the right thing. Also add some operator tests.
Turned logging off again in unit tests

Huge volume of logs makes it less useful, plus it will kill the build
server quickly (limited disk space etc.).

Calibrate/redo npgsql logging before reenabling this (#279)
Revert "Hacked nuget.targets to work on Windows/mono"

This reverts commit bf28c73be7d3327f0c9c5fe21e2abcc6441fcaf9.

See #137
Add timetz mapping for EF in provider manifest.
Fix precision extraction for interval type in NpgsqlSchema.ssdl.
Add support for DateTimeOffset/timestamptz casting in EF.
Add support for literal byte values (cast to int2) in EF.
Change literal time values to interval values in EF.
Add tests for operators, date functions and data types.
[MonoIgnore] on 2 tests

Fixes #288

Failures are a mono issue, see https://github.com/mono/mono/pull/1172
Merge branch 'master' of https://github.com/npgsql/Npgsql into operator-precedence-ef
Ignore failing EF tests on mono (probably due to bug in mono).
Small correction to [MonoIgnore]

Thanks @Emill
Merge pull request #287 from Emill/operator-precedence-ef

Fix operator handling and date functions for EF
Merge pull request #275 from franciscojunior/change-default-to-SSLStream

Make Npgsql use SSLStream for ssl connections instead of using Mono.Security